We investigated cisplatin resistant mechanisms in a cisplatin resistant ovarian cancer cell line (KFr) by means of flow cytometric analysis for damage of cisplatin to DNA base and DNA synthetic cells. Cisplatin showed cycle delay at 0.5 microgram/ml and then cycle arrest at 1 microgram/ml in G2 + M phase. KFr cells showed relatively rapid inhibition of DNA synthesis based with G-C base damage by cisplatin however, KFr cells had a capacity to repair DNA damage by cisplatin as showing cycle progression from G2 + M phase to G1-early S phase. Of the cisplatin derivatives tested which are of current clinical interest, Carboplatin and DWA 2114 R showed cross resistance to cisplatin in KFr cells.