A major problem in the management of incidental prostatic carcinoma (T1) is that the biological potential of these tumors varies across individuals. In 1975, Jewett suggested separating T1 tumors in two subgroups, called A1 (T1a) and A2 (T1b). The publications reviewed herein demonstrate that it is difficult to identify prognostic factors of potential usefulness for making therapeutic decisions in an individual patient with T1 prostatic carcinoma. Histological examination of tissue removed by transurethral resection or prostatectomy for benign prostatic hypertrophy does not allow determination of the size of the carcinoma or of its histological grade. A large number of patients with incidental carcinoma of the prostate also have other, independent prostatic tumors, especially in the outermost areas of the gland. Consequently, patients with incidental prostatic cancer should have additional diagnostic investigations including repeated prostate specific antigen assays, multiple biopsies, transrectal ultrasonography, computed tomography, and, if called for, magnetic resonance imaging. The value of second-look transurethral prostatic resection (TURP) for improving the accuracy of staging is controversial. This procedure may be indicated only in a small subgroup of carefully selected patients. Flow cytometry analysis of tumor cells may be useful for making therapeutic decisions in patients with T1 prostatic carcinomas. The progression rate in untreated patients with T1a tumors ranges from 16% to 36% and the proportion of patients with residual tumors after TURP is 40% to 80%. Based on these figures, radical prostatectomy can be considered the treatment of choice in young operable patients.