Aspiration biopsy is a rapid and relatively painless technique for evaluating an abnormal prostate gland. It can be performed on outpatients without anesthesia and is easily tolerated. It sensitivity in detecting cancer is at least equivalent to that of core biopsies, in part because several areas of the prostate may be sampled in a relatively atraumatic fashion. Few complications are encountered. Adequate performance of aspiration biopsy of the prostate requires experience and diligence, both by the urologist, in obtaining adequate specimens, and by the processing laboratory and pathologist, in interpreting these specimens. It is hoped that aspiration biopsy will lead to the early diagnosis of prostatic cancer, effecting lower morbidity, reduced hospital cost, greater ease in performing radical prostatectomy, and more accurate techniques for predicting the prognosis in affected patients.