This work serves as an investigation of the Isis cult by tracing its development from Egypt into Greco-Roman society. The origin of the Isis cult is described by using the accounts of Plutarch, Apuleius, and Diodorus before examining the effects of Isis on Egyptian culture. The Isis cult soon overflows into the Greco-Roman world. While this mysterious religion initially encounters opposition, especially since it clashes with Roman patriarchal society, it overcomes these limitations.