In a nonrandomized retrospective study, 133 patients with superficial transitional cell carcinoma of the bladder were evaluated to identify any clinical prognostic features which indicate the necessity of intravesical therapy (IVT). The risk factors taken into account were stage, grade and multiplicity of the tumour. All patients were treated initially by complete transurethral resection (TUR); 27 patients received no further treatment after resection of the tumour, 106 patients received adjuvant IVT over a period of 6 weeks. The mean follow-up was 23 and 18.8 months in the TUR-only group and TUR+IVT group, respectively. In the TUR-only group 7 and in the TUR+IVT group 29 recurrences were encountered. Patient group with no risk factors (Ta, GI, solitary tumour) or with only one risk factor revealed no statistical difference in terms of the recurrence rate from the identical control group. So it does not seem worthwhile to give additional therapy in the low-risk group. Another notable outcome of this study was that the higher the potential risk factors, the higher the likelihood of recurrence. The results suggest that T1 tumours, multifocal tumours, and high-grade tumours have poor prognosis, making additional treatment necessary.