Borderline ovarian tumours generally affect women of reproductive age. The positive prognosis is related to the fact that over 80% of cases are diagnosed at an early stage of the disease. Although radical surgery is the standard of care for this disease, fertility-sparing surgery can be performed in selected cases. Since it was first described in 1929, the knowledge of the molecular and histologic characteristics has been significantly improved. In this review, advances in the clinical behaviour, pathologic characteristics, prognostics factors, and different strategies of treatment are discussed.