An ovarian gynandroblastoma in a 60-year-old woman is described. The cut-surface of the right ovary showed multiple macrofollicles separated by white fibrous tissues and multiple ill-defined yellowish nodules. The tumour consisted of substantial amount of a granulosa cell element and a Sertoli cell element with intermingled Leydig cells. Immunohistochemically, the tumour cells in both the granulosa cell and Sertoli cell elements were positive for cytokeratin CAM5.2. The granulosa cell element showed strong membrane staining of Ewing's sarcoma antigen 013 and the Sertoli cell element was locally positive. Vimentin was observed in both the Sertoli cell element and the granulosa cells. Both elements and the Leydig cells were uniformly negative for epithelial membrane antigen, muscle specific actin, CD31 and CD34. The tumour was aneuploid by flow cytometry. The patient was well with no evidence of tumour five months after surgery.