This paper is concerned with the sculptural decoration of the Flavian sanctuary of Isis at Beneventum. It challenges the traditional “Egyptian” appearance of the sanctuary and suggests that “Graeco-Roman” elements, too, played a role in its sculptural decoration. Based on the analysis of a small group of Graeco-Roman sculptures, the paper also examines the association of Isis and Minerva and, ultimately, Magna Mater. The paper finally discusses the important role of this divine trinity, as well as the role of the Beneventan Iseum in relation to the official ideology of the Flavian emperors.