Aim: We report a case of proliferating Brenner tumour of the ovary, whichis a rare clinical entity. Case Report: A postmenopausal lady came with complaints of abdominal pain and distension for past 1 month. On examination, she had a uterine mass of 32 weeks size. Ultrasonography of the abdomen showed a cystic mass with multiple loculi havingirregular septations. Total abdominal hysterectomy with bilateral salpingo-oophorectomy was done. On gross examination, cut surface of the left ovarian mass revealed partly cystic and solid areas with yellowish white discolouration and papillary projections.On microscopic examination, multiple sections from the left ovarian mass showed well demarcated nests of epithelial cells resembling transitional epithelium, surrounded by stromal component of fibroblastic nature, with papillary formations at some places and coffee bean nuclei.The characteristic clinical and histopathological findings helped in clinching the diagnosis of proliferating Brenner tumour of the ovary. Discussion: Proliferating Brenner tumours are a type of surface epithelial stromal tumours of the ovary and they have to bedistinguished from their benign and malignant counterparts. Presence of papillary projections in the cystic areas of the tumour on gross examination as well as in microscopy,hintthe diagnosis of proliferating Brenner tumour. Malignant Brenner tumours have cellular atypia and stromal invasion. Conclusion: Prompt and correct diagnosis of the Brenner tumour of ovary and its sub-classification forms the basis for its correct management. This can be achieved with the knowledge of its characteristic histopathological findings discussed in this case report.