The role of adjuvant irradiation in the treatment of transitional cell carcinoma of the renal pelvis and ureter was reviewed. Between June 1966 and March 1981, 41 patients underwent curative resections. A poor risk group was identified, with 23 patients demonstrating disease greater than grade 2 or stage B. Postoperative irradiation was administered to 11 of 23 patients. Median patient followup was 40 months. Two-thirds of all failures occurred within the first 12 months and no failure was seen beyond 35 months. Patients with poor prognostic features had a 60 per cent failure rate compared to 11.8 per cent of the patients with good risk factors (p equals 0.023). The median survival of the 2 groups was 28 and 99 months, respectively (p less than 0.001). Outcome of the poor risk patients was analyzed whether or not the patient received postoperative irradiation. None of the irradiated patients failed with local disease only, while there was 1 patient with local and distant recurrence. In contrast, the nonirradiated group had 5 local failures and twice the number of failures over-all. Median survival of the irradiated and nonirradiated patients was 35 and 26 months, respectively. The number of patients treated is too small to permit valid statistical conclusions and indicates the need for a multi-institutional study to determine if these suggestive findings of improved local control will be corroborated and translate into an improved survival rate.