The objective of this study was to review the results of our policy of primary radiotherapy (RT) and salvage cystectomy for transitional carcinoma (TCC) of the bladder in the light of changes in our radiotherapy planning procedure, in particular the introduction of CT planning. The case notes of 163 patients treated with radical radiotherapy using a CT planning technique were examined. The main endpoint for assessment was response at the time of the check cystoscopy 6 months after the completion of treatment. In addition survival was estimated by stage of disease and by response at the time of first cystoscopy. Patterns of relapse and time to relapse were analysed. All percentages quoted in the text use the initial 163 patients as the denominator. One hundred patients (61%) achieved a complete response. The complete response rate was significantly related to T stage at presentation being 90% for T1, 75% for T2, and 53% for T3 disease respectively. Of these patients 78 remain disease free in the bladder (47%). Twenty-two have relapsed in the bladder, of whom 5 have also relapsed at metastatic sites. Fifteen patients have relapsed outside the bladder whilst remaining disease free within the bladder. At the time of last follow up or death from other causes 63 of the 100 patients who had a complete response remained disease free with an intact bladder. There were 18 (11%) partial responders. Seven of these patients went on to have a cystectomy. Ten remain alive, 7 disease free, 4 with intact bladders. In 24 patients (15%) there was no response and these patients have all died, the median survival being 10 months. In 21 patients (13%) a postradiotherapy cystoscopy was not performed. In all but one patient, who was lost to follow up, this was because of progressive disease. The median survival of these 20 patients was 6 months. Of the 163 patients 35% are alive and well with an intact bladder. If patients dying from other causes are included then 42% were rendered disease free. Cause specific survival was significantly related to stage of disease at presentation with 5 year actuarial survival being 87%, 48% and 26%, for T1, T2 and T3 disease respectively. Survival was also related to response to treatment at 6 months with 5 year survival being 64%, and 52% for complete and partial responders respectively. Survival was extremely poor for non-responders with only 37.5% surviving 1 year and none 5 years. There was a highly significant relationship between response and the development of, and the time to developing metastatic disease. Of those who exhibited a response 21% developed metastatic disease compared to 78% of non-responders. Salvage cystectomy offers the possibility of cure in those who achieve a complete or partial response with 42% of such patients being rendered disease free. Results however are poor in those who did not respond with all patients dying of their disease. Response rates for all stages, and survival for stages T1 and T2 are much improved from those previously reported from this centre and compare favourably with other published series. These results confirm the place of radiotherapy and salvage cystectomy in the management of TCC of the bladder in selected patients. In about one-third of patients the desired outcome of curing the patient of their cancer with organ preservation is achieved. The prognostic significance of cystoscopic response at 6 months and stage at presentation is confirmed. The outcome for patients with early stage disease is excellent. The relationship between response and the development of metastatic disease would suggest that even if these patients had had a primary cystectomy they may have fared badly, a conclusion supported by the fact that these results are comparable with surgical series. This series supports the role of radiotherapy in the management of this disease and suggests that modern RT techniques including CT planning have had a beneficial effect on the results of radical radiotherapy.