The Protestant Old Testament contains 39 books, but that number is not universal. The Catholic Old Testament includes 46. Eastern Orthodox canons count 49 to 51, depending on jurisdiction. The Ethiopian Orthodox tradition includes more still. The question “how many books are in the Old Testament?” turns out to have no single answer — it depends on which Christian tradition is doing the counting and which collection of ancient Jewish texts that tradition adopted as authoritative.
This is not a modern disagreement. The variation goes back to the earliest centuries of Christianity, when different communities inherited different collections of Jewish scriptures and made different decisions about which texts carried canonical weight. Understanding why the numbers differ means understanding two competing collections — the Hebrew Bible and the Septuagint — and how their divergence shaped Christian canons for the next two thousand years.
The Protestant Old Testament: 39 Books
The Protestant Old Testament contains 39 books, arranged in a sequence that begins with Genesis and ends with Malachi. These books are typically grouped into four categories: the Pentateuch (Genesis through Deuteronomy), the Historical Books (Joshua through Esther), the Poetical or Wisdom Books (Job through Song of Solomon), and the Prophets (Isaiah through Malachi).
This 39-book collection matches the content of the Hebrew Bible, though not its structure. The Hebrew Bible (Tanakh) organizes the same material into 24 books across three divisions: Torah (5 books), Nevi’im or Prophets (8 books), and Ketuvim or Writings (11 books). The difference in count — 39 versus 24 — comes entirely from how books are divided. The twelve Minor Prophets (Hosea through Malachi) are a single scroll in the Hebrew Bible but twelve separate books in the Protestant canon. Samuel, Kings, and Chronicles are each one book in Hebrew but split into two in Christian Bibles.
The content is the same. The packaging is different.
During the Reformation, Martin Luther and other Protestant reformers returned to the Hebrew Bible as the standard for the Old Testament, arguing that only books preserved in Hebrew should be considered canonical. This decision excluded the additional texts found in the Septuagint — a consequential choice that permanently separated the Protestant Old Testament from the Catholic one.
The Catholic Old Testament: 46 Books
The Catholic Old Testament includes everything in the Protestant canon plus seven additional texts: Tobit, Judith, Wisdom of Solomon, Sirach (also called Ecclesiasticus), Baruch (including the Letter of Jeremiah), and 1-2 Maccabees. Catholics also include longer versions of Daniel and Esther that contain passages not found in the Hebrew text.
These additional books are called the deuterocanonical texts — literally “second canon” — a term that reflects their status as authoritative but distinct from the books shared with the Hebrew Bible. They were composed during the Second Temple period, roughly 200 BCE to 100 BCE, and they appear in the Septuagint, the Greek translation of the Hebrew scriptures produced in Alexandria beginning in the 3rd century BCE.
The Septuagint was the Bible of the early church. Greek-speaking Christian communities from the 1st century onward read and quoted from this broader collection, and several New Testament authors appear to draw on deuterocanonical texts — the Letter to the Hebrews echoes language from Wisdom of Solomon, and the Letter of James parallels passages in Sirach. The scholar Albert Sundberg argued in the 1960s that the Septuagint’s broader collection represented the scriptures as early Christians actually used them, not a later addition.
The Catholic canon was not formally defined until the Council of Trent in 1546 CE, during the Reformation. Trent’s decree was partly a response to Protestant reformers who had excluded the deuterocanonical books. The council declared these texts fully canonical — not secondary, not optional, but part of the inspired Old Testament.
The Orthodox Canons: 49 to 51 Books
Eastern Orthodox traditions include everything in the Catholic Old Testament plus additional texts, though the exact list varies by jurisdiction.
The Greek Orthodox canon adds 1 Esdras, the Prayer of Manasseh, Psalm 151, and 3 Maccabees. The Russian Orthodox canon is slightly different. The Georgian and Armenian traditions have their own variations. The lack of a single universal Orthodox council defining the canon means that Orthodox churches operate with broadly similar but not identical lists — a situation that has persisted for centuries without creating a theological crisis.
The Ethiopian Orthodox canon is the most expansive in Christianity, including texts like 1 Enoch, Jubilees, and other works that appear in no other Christian tradition’s canon. 1 Enoch, composed over several centuries beginning around 300 BCE, was widely read in Second Temple Judaism and is quoted directly in the New Testament Letter of Jude (Jude 14-15). Its inclusion in the Ethiopian canon reflects the distinctive history of Ethiopian Christianity, which developed in relative isolation from the Roman and Byzantine traditions that shaped Western and Eastern Orthodox canons.
The scholar Lee Martin McDonald, in The Biblical Canon: Its Origin, Transmission, and Authority (2007), emphasizes that these variations are not anomalies — they reflect the normal state of affairs throughout most of Christian history. A single fixed canon was never the universal reality. Different communities preserved different collections, and the boundaries remained more fluid than most people assume.
Why the Count Differs: Hebrew Bible vs. Septuagint
The root of all these variations lies in a fork that occurred centuries before Christianity existed.
By the 3rd century BCE, Jewish communities in Alexandria — Greek-speaking and culturally integrated into the Hellenistic world — began translating their scriptures into Greek. This translation, the Septuagint, included texts that had been composed in Greek or preserved only in Greek, alongside translations of the Hebrew originals. The result was a broader collection than what Palestinian Jewish communities were using in Hebrew and Aramaic.
When Christianity emerged as a largely Greek-speaking movement in the 1st century CE, it adopted the Septuagint as its scriptures. The Hebrew-speaking rabbinic tradition, meanwhile, consolidated around a narrower collection. By the 2nd century CE, the paths had diverged: the emerging Christian Old Testament was broader, and the emerging rabbinic Bible was narrower.
Protestant reformers in the 16th century chose the narrower collection. Catholic and Orthodox traditions retained the broader one. The numbers — 39, 46, 49, 51 — are the legacy of that ancient fork.
| Tradition | OT Book Count | Standard |
|---|---|---|
| Protestant | 39 | Hebrew Bible (Tanakh) |
| Catholic | 46 | Septuagint tradition, defined at Trent 1546 |
| Greek Orthodox | ~49 | Septuagint + additional texts |
| Ethiopian Orthodox | ~51+ | Broadest Christian canon |
What This Means for Reading
The variation in Old Testament book counts is not a problem to be solved. It is a feature of the Bible’s history — evidence that the biblical canon was never a single, fixed entity but a living collection whose boundaries were drawn differently by different communities for different reasons.
When someone asks “how many books are in the Old Testament,” they are asking a question that assumes a single answer exists. The history suggests otherwise. Thirty-nine books if you follow the Protestant tradition and its alignment with the Hebrew Bible. Forty-six if you follow the Catholic tradition and its roots in the Septuagint. More if you follow Orthodox traditions that preserved an even broader collection.
Each number tells a story about which community did the counting, which ancient collection they inherited, and which texts they judged authoritative enough to bind between the covers of their Bible.
For the companion question about the other half of the Christian Bible, see How Many Books Are in the New Testament? — where the answer, unlike the Old Testament, is remarkably consistent across traditions. And for the full list of texts that appear in some Bibles but not others, see What Are the 14 Books of the Apocrypha?
Uncanon presents the Old Testament in the order scholars think these texts were composed — from the 8th-century BCE prophets through the Hellenistic-era writings — with historical context before every passage. If you want to explore how the 39 books of the Protestant canon (or the broader collections) came to be arranged and read, How Was the Bible Put Together? is where the full story unfolds.