In this study the scanning and transmission electron microscopical, features of parovarian cysts were analyzed to further the determination of histogenesis, development, classification and differential diagnosis of these lesions. Paramesonephric type lesions showed ciliated and microvillous cells, sometimes in a wavy arrangement with grooves and holes, similar to the oviduct epithelium. The mesonephric type consisted of an epithelium of tightly arranged angular cells with minimally developed surface structures. Destruction of specialized surface structures was frequently seen, epithelial proliferation was uncommon.