Echinococcus granulosus is considered the major cause of humanhydatid cysts. Usually the duration of cyst formation is 10-20 years. This period shortens significantly upon rupture of aprimary cyst. The literature describes low incidence of primaryinvolvement of ovary as a site of hydatid cyst formation. Ourcase is the first report on ovarian hydatid cyst in Iran. A 60-year-old woman was presented with abdominal pain in the leftlower quadrant area. Paraclinical data were suggestive of neoplasiaand preoperative diagnosis was ovarian tumor. Duringlaparotomy, multiple cysts resembling hydatid cysts were observedin the left ovary. Pathological examination confirmed thediagnosis of hydatid cyst. Although there is a small possibilityof secondary ovarian echinococcal disease, it is more probablefor this case to be primary infection, as the patient had developedovarian hydatid cysts 15 years after hepatic involvementand recurrence after 30 months is very uncommon