Recent interest in intravesical instillation of bacillus Calmette-Guérin for the management of carcinoma in situ (CIS) of the bladder prompted us to review our results of total immediate cystourethrectomy. From 1975 to 1987, we surgically treated 302 patients with primary bladder tumours. Of these, 21 bladder tumours were histologically diagnosed as CIS, and total immediate cystourethrectomy was performed in all cases. The lesions were classified into three types: primary CIS accompanied by neither previous nor simultaneous tumours of the urinary tract (Type 1, 9 patients), concomitant CIS associated with superficial papillary tumour (Type 2, 6 patients), and secondary CIS detected during the follow-up period after treatment of the superficial papillary tumour (Type 3, 6 patients). Primary CIS was more often diagnosed according to subjective symptoms such as micturition pain than concomitant CIS. Secondary CIS was diagnosed in all patients by routine examinations including cytology and cystoscopy. There was no particular relationship between the time of recurrence of the tumour and the occurrence of secondary CIS. Within the same period, 60 patients with stage T1 bladder tumour were treated by total cystourethrectomy. The actuarial 5-year survival rate was 77% for T1 and 75% for CIS. The 5-year survival rate was 71% for Type 1, 83% for Type 2, and 67% for Type 3 CIS with no difference among the CIS types. Tumour invasion to the bladder, prostate, ureter, or lymph nodes was observed in 9 (42.9%) of the 21 patients, although cystourethrectomy was performed within 3 months of the diagnosis. Examination of ABH antigens did not allow prediction of invasion of CIS. Our findings suggest that the invasive potential of CIS may seriously limit the indications of conservative treatment against carcinoma in situ.