A multicenter cooperative study was conducted to evaluate the clinical efficacy and safety of cis-diammine(glycolato)platinum (254-S), a second-generation anticancer platinum complex, in the treatment of genitourinary cancers. 254-S was given i.v. at 100 mg/m2 at 4-week intervals. As a result, 2 complete responses (CRs) and 8 partial responses (PRs) were obtained in 35 patients with transitional-cell carcinoma (TCC) of the urinary bladder or pyeloureter, 3 PRs were obtained in 16 subjects with prostatic cancer, and 6 CRs and 6 PRs were obtained in 15 patients with testicular cancer, generating objective response rates of 28.6% [95% confidence interval (CI), 14.6%-46.3%], 18.8% (95% CI, 4.0%-45.6%), and 80.0% (95% CI, 51.9%-95.7%), respectively. Bone marrow suppression was the dose-limiting toxicity, although it was reversible. Although no hydration was performed in approx. 40% of the patients, the incidence of nephrotoxic effects was low and most of those encountered were mild, the exception being one patient who showed severe renal insufficiency after the first treatment. Nausea and vomiting occurred in approx. 70% of the patients, but most gastrointestinal toxicities were controlled without antiemetic treatment. In addition, liver-function impairment was rarely observed. We conclude that 254-S is a promising cisplatin analogue for the treatment of genitourinary cancers and is worthy of further investigation in large-scale, randomized comparative studies with other platinum derivatives in both single-agent and combination regimens.