The «Physiologus», an early Christian writing in Greek (ca. 200 A.D.), consists of cameo stories about the nature of animals, with a religious interpretation of their peculiarities. It was widespread during the Middle Ages in various languages. The study of more than forty manuscripts of the Armenian «Physiologus» reveals its main recension (ms M2101 and others), translated during the first half of the fifth century, and two subsequent recensions. The translation is close to the eleventh century Greek Codex Mosquensis (Synodal Library 432). The «Physiologus» had widespread influence in both eastern and western writings, and the Armenian version is one of the oldest and most faithful witnesses. In addition, the "revised diplomatic edition" of the parallel Greek and Armenian texts based on the mentioned manuscripts, regards variant readings which bring the two texts close to each other, helping to reconstruct their archetype.