Brenner tumours of the ovary are uncommon neoplasms and mostly benign. There is general agreement that Brenner tumors are derived from the surface epithelium of the ovary or the pelvic mesothelium through transitional cell metaplasia. It is essential to categorise these tumours as benign, borderline or malignant type as the biologic behaviour and choice of surgery differs in all of the three categories. The authors report a case of Brenner tumour that had only a single area with a beginning indistinct stroma vessel invasion. However the presence of characteristic epithelial nests, fibromatous stroma, and marked cytological metaplasia without atypia provided important clues to the correct diagnosis--proof of a benign tumour.