In contrast with other malignant tumors, the prognosis of malignant ovarian mucinous tumors has not been improved. In fact, their are diagnosed late and their therapy is often inadequate. The absence of consensus concerning the histological criteria of borderline tumors and mucinous carcinomas has led to diverse classifications which are often not reproducible and are also responsible for heterogeneous results concerning patient survival. Unfortunately, none of the biochemical, molecular biology or cytometric markers which have been studied up until now can be used for differential diagnosis. Another particularity of mucinous tumors consists of their association with other ovarian tumors, mural nodules which are reactive or tumor proliferations and which might influence the prognosis of the mucinous tumor, when their are malignant, and peritoneal pseudomyxoma and appendicular mucocele which give rise to problems related to their relation.