Phase I study of DWA2114R, a new platinum analogue, was conducted in 39 patients with various tumor types by a group of 13 institutions. Of the 39 patients entered in this study, 35 were evaluable. The starting dose was 40 mg/m2 (1N) and the drug was administered i.v. for 20-30 min, escalating stepwisely up to 1,000 mg/m2 (25 N). The dose limiting factor (DLF) was leukocytopenia, especially neutrocytopenia, and the maximum tolerated dose (MTD) was more than 1,000 mg/m2. Major clinical toxicity was gastrointestinal. Hepatotoxicity and nephrotoxicity were mild. Following administration of the drug, plasma concentrations of total and filterable platinum (Pt) showed a triphasic and biphasic decays. Excretion into urine within 24 hours was in the range of 54.2% to 92.2% of the administered platinum. The recommended dose of phase II study was 800-1,000 mg/m2, repeating every 3-4 weeks.