A case of a 41-year old woman with an enlargement of the inferior part of the abdomen is presented. An echographic examination established the diagnosis of a right ovarian cyst. During the operation, a 14-cm (5 1/2") tumor, presenting a large ruptured cyst and solid mass, was found. From the cystic activity, a viscous fluid was oozing. On the left ovary, a 4 cm (1 1/2") cyst was also found. Within this case report, we underline the unusual association of a mucinous papillary cystadenocarcinoma with an arrhenoblastoma in the right ovary together with the presence of an cystadenoma in the left ovary.