To study the clinical and pathological factors that affect recurrence, progression and survival in pT1G3 bladder tumours treated conservatively. From January 1979 to December 1996, 80 patients were conservatively treated for pT1G3 bladder tumours. All patients were studied for potential prognostic factors such as: age, sex, previous tumour recurrence, tumour size, multiple tumours, carcinoma in situ, and intravesical instillations. A longitudinal, retrospective, observational and analytical study was conducted to evaluate four different types of events: recurrence, progression, overall survival, and disease-specific survival. The chi(2) (Fischer exact test) and student t tests were used to assess the prognostic value of the qualitative and quantitative variables. Estimations of the survival distributions were calculated according to the Kaplan-Meier method and compared with the Log rank test. Multivariate analysis of the data was performed with Cox proportional hazard models. Among the 80 patients, 67 (84%) were men and 13 (16%) were women, with median age of 65.5 years. The median tumour size was 20 mm, most had single tumour (58.8%) and carcinoma in situ was found in six patients (7.5%). Thirty patients were treated with transurethral resection (TUR) of the bladder tumour and 50 patients were treated with TUR followed by BCG. The two groups of patients were comparable and followed up during a median time of 61 and 65 months, respectively (p=0.454). Kaplan-Meier estimators and Log rank tests demonstrated that patients with TUR alone recurred (p<0.0001), progressed (p<0.040) and died (overall survival: p<0.009; disease-specific p<0.040) earlier than patients who received intravesical instillations of BCG. The results were confirmed with Cox models and odds-ratios are presented. In this study, BCG adjuvant immunotherapy was the only factor affecting recurrence, progression and survival. Conservative treatment using TUR followed by BCG may improve disease-specific survival.