Clear cell tumours of the ovary are relatively uncommon. Most of them are clear cell carcinomas. Benign and borderline clear cell tumours are extremely rare and almost always fibromatous. We report a case of a 34-year-old woman. Ultrasound and computed tomography showed a right ovarian mass 8 cm in diameter. The patient underwent right salpingo-oophorectomy. Microscopic examination revealed glands and cysts different in size and shape within an abundant stromal component without evidence of stromal invasion. Many cysts and glands were lined by a single layer of flattened, cuboidal or hobnail cells with mild to moderate cytologic atypia and prominent nucleoli. Psammomatous calcifications were occasionally indentified. Features of endometriosis were also present adjacent to the tumour. Lesional cells were positive for Ker 7 and CA125. Staining for p53 was focally positive. Based on the above characteristic morphologic and immunohistochemical findings a diagnosis of borderline clear cell adenofibroma was made. The patient was free of recurrence four years after surgery.