The prognostic value of prostate involvement in patients with superficial bladder cancer was analyzed. We studied 96 patients with prostate involvement. Taking progression-free survival rate as an end point, univariate and multivariate analyses were done. The presence or absence of bladder carcinoma in situ is related to poor and good prognoses, respectively (p less than 0.001). Stromal invasion (p less than 0.001) and pan-urothelial involvement (p = 0.03) were also identified as independent factors of poor prognosis. Patients with tumor limited to the mucosa can be treated conservatively. Cystoprostatectomy can be performed in patients with ductal involvement. The prognosis of patients with stromal invasion is poor despite radical treatment.