To determine the clinical characteristics of grade 3 tumors with lamina propria invasion (pT1), we reviewed the data of 217 patients with superficial bladder cancer who had initially been treated by transurethral resection (193 patients) and fulguration (4), supravesical resection (13) or partial cystectomy (7). We classified the patients into four groups according to histological grade and stage of disease: group 1) grade 0 or 1, pTa tumors (n = 58); group 2) grade 2, pTa tumors (n = 106); group 3) grade 2, pT1 tumors (n = 30); and group 4a) grade 3, pT1 tumors (n = 23). Grade 3, pT1 tumors were significantly related to nonpapillary growth (p = 0.0002), multiple tumors (p = 0.005) and irritative bladder symptoms (p = 0.01). The 5-year progression rates were 0% for group 1, 5% for group 2, 8% for group 3, and 18% for group 4a. The respective 5-year survival rates were 97%, 91%, 83% and 79%. All five patients with grade 3, pT1 tumors who had originally undergone total cystectomy (group 4b) remained alive free of disease for a median follow-up 57 months, establishing a far better survival rate than that for group 4a. These findings show that patients with grade 3, pT1 tumors face a high probability of progression and poor chance of survival. Immediate radical treatment is indicated when tumors recur after initial transurethral resection.