Splenosis is a very rare entity that often appears following a traumatic rupture of the spleen or after splenectomy and represents heterotopic transplantation of splenic tissue. The ovary is reported as an atypical and rare localization. We report a case of a middle-aged woman, which presented with a left adnexal mass. Transvaginal ultrasonography, computed tomography (CT) and high-field 3T magnetic resonance imaging (MRI) revealed the left adnexal mass. Laparoscopy was performed, and histological and immunohistochemical examination revealed that resected mass was splenic tissue.