This is a Latin translation made in the mid-12th century of a lost Arabic astrological text on nativities and anniversaries, probably by Masha'allah (762-c.815). The Latin text, the work of Hugo of Santalla, who was in the entourage of Michael, Bishop of Tarazona, in 1145, sheds light on the early stage of Arabic astrology in Baghdad, which was based on Greek and Middle Persian sources, and it includes a bibliography of these sources. This work provides English translations of the parallel passages based on Masha'allah’s text - the Book of Nativities of Sahl b. Bishr. The book concludes with an index of the sources mentioned and a comprehensive word index.