Sclerosing stromal ovarian tumor is an extremely rare neoplasm occurring predominantly in the second and third decades of life. It presents most often with non-specific symptoms. We describe a new case occurring in a young woman presenting with infertility and irregular menses. Ultrasound examination showed a left heterogenous ovarian mass without focal calcifications. Histological features included a pseudolobular pattern with focal areas of sclerosis, prominent vascularity and a two-cell population of spindled and poly­gonal cells. Immunohistochemical analysis for actin, vimentin, laminin, vascular epidermal growth factor (VEGF), oestrogen and pro­gesterone receptors using formalin-fixed and paraffin-embedded materials showed predominant positivity for a-smooth muscle actin. and consistent positivity for laminin and vimentin. The epidermal VEGF demonstrated rich tumor vascularity. Oestrogen and progesterone receptors were not expressed, suggesting hormonally independent development. Menstrual cycle disturbances, however, were corrected following extirpation of the tumor, indicating some endocrine involvement. In addition, the patient became pregnant ten months after the operation. The differential diagnosis is discussed.