Twenty patients (17 M., 3F., -mean age 61.5 yrs) affected by superficial bladder tumors (TINOMO) were included in the study. All patients had cold mucosa biopsy to exclude the presence of dysplasia or CIS; the histopathological grade was G1 in 19 cases and G2 in 1. The treatment was started between 3 to 7 days after radical TUR with intravesical instillations of recombinant Interferon alfa 2a, at the daily dose of 54 million/Units for 5 days for 2 consecutive weeks. No systemic adverse effects were observed. Local toleration and efficacy were assessed by cystoscopy, performed at the end of treatment after 6 weeks and then at three month intervals. At the first control 15% of patients showed an early local reaction with bollous oedema surrounding the resected area (with spontaneously disappeared after few days). No other abnormal findings were observed at the 6-week control. After a median follow-up of 98 weeks, 15 of the 19 evaluable patients (79%, C.I. 60-91) were disease-free. The median relapse time was 39.9 weeks, while clinical and local tolerance were optimal. These preliminary data confirm the complete absence of toxicity of Interferon alfa 2a administered at relatively high doses intravesically and indicate that this compound has some effect on superficial bladder cancer.