Malignant epithelial tumours (carcinomas) are the most common ovarian cancers and the most lethal gynaecological malignancies. Based on light microscopy and molecular genetics, ovarian carcinomas are subdivided into at least five main subtypes that account for over 95% of cases and are inherently different diseases, as indicated by differences in epidemiological and genetic risk factors, precursor lesions, patterns of spread, molecular events during oncogenesis, response to chemotherapy and outcome. For successful subtype-specific treatment, reproducible pathological diagnosis of tumour cell type is critical. Recent investigations have also demonstrated that a significant number of cancers traditionally thought to be primary ovarian tumours (particularly serous, endometrioid and clear cell carcinomas) originate in the fallopian tube and the endometrium and involve the ovary secondarily. In this review we summarise recent advances in the molecular pathology, which have greatly improved our understanding of the biology of ovarian carcinoma and are also relevant to patient management.