A total of 34 patients with grade 3 carcinoma in situ of the bladder entered a phase 1/2 study with epirubicin to examine the rate of antitumor activity, the type and frequency of local side effects, and the absorption and recovery rates. The selected doses were 30, 50 and 80 mg. Of the patients 22 were evaluable for report of treatment results. A total of 16 patients had a complete remission proved by biopsy and conversion of urine cytology findings. Mean duration of complete remission was 22.4 months (range 7+ to 50+ months). After a mean followup of 35.3 months (range 14 to 59 months) 8 of 16 patients were still in complete remission, 3 died of a myocardial infarction, 3 had recurrent grade 3 carcinoma in situ, 2 had increase to a higher T category (stages T2 and T4a), and 2 had recurrent papillary stage Ta, grade 2 (1) and stage T1, grade 2 (1) transitional cell carcinoma of the bladder. Six of the 22 patients had no response to 1 or 2 treatment courses with a higher dose. Plasma concentrations of epirubicin after instillation were close to the detection limit of the assay (0.5 to 2.0 ng/ml. plasma).