The relevance of 3H-thymidine labeling index (3H-dt LI) on clinical outcome was evaluated on 85 patients with advanced ovarian cancers treated with carboplatin or cisplatin alone (39 cases) or cisplatin in association with doxorubicin and/or cyclophosphamide (46 cases). 3H-dT LI of the primary tumour was significantly related to the 3-year probability of survival in patients treated by monochemotherapy (low LI, 63%; high LI, 21%; P = 0.013) but not in those treated with polychemotherapy. Analysis of the relation between cell kinetics and clinical outcome as a function of treatment showed that in patients with rapidly proliferating tumours the 3-year survival was significantly higher following polychemotherapy than monochemotherapy (51 vs. 21%; P = 0.04). In patients with slowly proliferating tumours no significant difference in survival was observed following the two types of treatment for the overall series, whereas in patients not achieving a complete response survival was significantly higher following monochemotherapy than polychemotherapy (61 vs. 9%; P = 0.008).