Improved early detection of recurrence in prostatic carcinoma following hormonal therapy. Combined use of palpation and fine needle aspiration cytology. Fifty-nine hormonally treated prostatic carcinoma patients were prospectively followed by rectal examination and fine needle aspiration cytology at six-month intervals for periods ranging from six to one hundred twenty months (median follow-up 48 mos). The cytologic findings and clinical impressions were divided into four or five categories, respectively, ranging from benign to clearly malignant. Cytologic material and clinical descriptions suitable for evaluation were available for 306 follow-up examinations. Of these, 209 were cytologically benign (including 191 without and 18 with clinical evidence of malignancy). The remaining 97 examinations showed cytologic evidence of malignancy of which 50 were clinically apparent (51.5%). While the correlation of clinical and cytologic findings was good (91.4%) in cases with no evidence of disease activity, our findings indicate that many recurrences which are occult to clinical examination may be detected by cytologic examination. 