Collision tumor means the coexistence of two adjacent tumors, but histologically distinct without mixture into the fabric. These tumors involving the ovaries are rare. Benign cystic teratomas are often present at the same time as other abnormalities of the ovary. The most common histological combination in the ovary is the coexistence of cystic mature teratoma with mucinous tumors, its association with serous tumors is rare and the incidence is unknown. Ovarian mature cystic teratomas are benign often diagnosed in young girls. We present a rare case of a triple coexistence of a large tumor collision (consisting of a serous cystadenoma, mucinous cystadenoma and a mature cystic teratoma Benin) in the same ovary in a girl of 16 years.