The aim of this study was to evaluate the efficacy and safety of gemcitabine, a pyrimidine antimetabolite, in the treatment of advanced transitional cell carcinoma of the urinary tract. 35 patients with unresectable or metastatic transitional cell carcinoma of the urinary tract previously treated with a platinum-based regimen were studied. Gemcitabine was administered at a dosage of 1200 mg/m2 as a 30-min intravenous infusion on days 1, 8 and 15, repeated every 28 days. 31 patients were evaluable for efficacy. 4 patients achieved a complete response (12.9%), 3 a partial response (9.6%) and 13 (42%) were stable for at least 4 weeks (overall response 22.5%; 95% confidence interval 8-37%). The median response duration was 11.8 months (range 3.6-17.7 + months) and median survival for all patients entered was 5 months (range 2-21 + months). 2 patients with complete response are still alive with no evidence of disease after 14 and 21 months. Gemcitabine also provided subjective symptomatic relief from pain, cystitis, dysuria, haematuria and peripheral oedema. Patients experienced little WHO grade 3-4 toxicity, with anaemia in 8 patients (23%), thrombocytopenia in 5 (14.2%), leucopenia in 4 (11.4%) and neutropenia in 7 (20%). WHO grade 3-4 hepatic toxicity occurred in 4 patients (11.4%) and transient elevations of transaminase was noted in 3 (8.6%). No patient had WHO grade 3-4 elevation of serum creatinine level. There was no WHO grade 4 symptomatic toxicity and no alopecia was noted. Transient influenza symptoms with gemcitabine occurred in 18 patients (51.4%) with 13 patients (37.1%) experiencing fever (2.9% WHO grade 3). In conclusion, gemcitabine is an new active agent for the treatment of transitional cell carcinoma of the urinary bladder with a mild toxicity profile; it warrants further investigation in combination with cisplatin in chemotherapy naive patients.