We evaluated the effects of cisplatin on the cell kinetics, cytomorphological changes, and cleavage patterns of DNA in two lines of human ovarian carcinoma cells. KF-1 cells displayed a cell cycle arrest in the G2M phase, while HMG cells displayed a transient cell accumulation in the S phase, without obvious G2M arrest. Morphological changes characterized by condensation and fragmentation of chromatin, and DNA cleavage by oligonucleosome-sized DNA fragments were observed in the HMG cells but not in the KF-1 cells. The pattern of cell death in HMG cells was considered to be apoptosis, but that of KF-1 cells necrosis. These findings showed the different mechanisms of anti-tumor effect of cisplatin on human ovarian carcinoma cell lines, including cell kinetics and pattern of cell death.