Planning treatment for patients diagnosed with stage A prostate cancer by transurethral resection or open enucleation can be difficult. Inability to determine the presence or absence of significant residual disease can result in unnecessary treatment for some individuals and inadequate treatment in others. Transrectal ultrasound imaging and systematic prostate biopsies offer a potential means of evaluating these patients. To determine the rate of residual cancer detection 3 groups of stage A prostate cancer cases were evaluated. Group 1 consisted of 39 patients who underwent radical prostatectomy. Preoperative ultrasound imaging revealed residual cancer in only 24%. Transrectal ultrasound guided systematic biopsies were performed in group 2 (25 patients) and revealed cancer in only 28%. Based on prior morphometric studies of prostatectomy specimens from stage A cases, a modification of the systematic biopsy method, which included anteriorly directed biopsies, was developed and applied to group 3 (47 patients). Cancer was detected in 47% of the patients, and it was detected by additional anterior biopsies alone in 11%.