Sixty-four patients with multiple, superficial papillary bladder tumours which had ceased to be controlled by endoscopic resection and diathermy were treated before July 1972 with intravesical Epodyl instillations. Of these, 19 had developed no further recurrences; 20 patients were free of tumour to one year, but later developed recurrences. Twenty-four patients were never entirely free of tumour after starting Epodyl and one patient became free of recurrences 2 years after starting Epodyl. Only the patients whose histology showed no invasion of the lamina propria responded to treatment. The overall 5-year survival rate was 66%, with a disease-free interval of 61% at one year and 25% at 5 years. Failure to clear the bladder of tumour after 12 months' treatment, or worsening of biopsy stage from PIS to Pla or Plb while on treatment, were associated with a high risk of dying of invasive tumour and in future should be used as immediate indications for radical treatment.