The diagnosis of an androgen-secreting tumour of the ovaries should be considered in women with hyperandrogenism. Clinical manifestations of hyperandrogenism include virilisation with hirsutism, vocal change, increased muscle mass, hypertrophy of clitoris and alopecia. Definitive diagnosis is made by histopathologic examination, and the most common diagnoses are granulosa cell tumour, ovarian stromal hyperplasia and Sertoli-Leydig cell tumour. The differential diagnoses include polycystic ovary syndrome, benign or malignant adrenal tumour and adrenal hyperplasia.