Introduction: Hydatid disease is a zoonosis caused by the larval stages or the adult of tapeworm Echinococcus granulosus or less commonly Echinococcus multilocularis. It is prevalent in the areas where livestock is raised in association with the dogs. Humans are accidental intermediate host. Primary ovarian hydatid cyst is extremely rare and often mistaken as cystic tumors of the ovary. Case report: We present a rare case of a 38 years old woman who presented with intermittent dull aching pain in the lower abdomen since 6 months. Ultrasonography of whole abdomen revealed the evidence of a left adnexal cystic lesion. Exploratory laparotomy was performed and a left ovarian cystic mass was identified. The cyst was removed intact. Histopathological examination confirmed it to be a hydatid cyst. Conclusion: Removal and proper treatment of the infected animals, interrupting the cycle of transmission of hydatid cyst, help to eliminate the disease. The implementation of public awareness of the disease and proper sanitation are needed to prevent this disease. Primary ovarian hydatid cyst is rare and requires proper intraoperative management to avoid spillage and thereby recurrences. Then the patients are treated with anthelmintics. Keywords: Echinococcosis, Hydatidosis, Echinococcus granulosus, Echinococcus multilocularis, hydatid cyst, laparotomy, ovary, surgery