The purpose of this study was to find out whether randomly taken fine needle aspiration biopsy (FNA) can detect incidental prostatic carcinoma prior to transurethral resection (TUR) and what are the effects of local tumor stage and grade on detection rate. Biopsies were taken from 344 patients, who came to hospitals for elective TUR without clinical evidence of prostatic carcinoma. Histologic examination of the TUR material showed prostatic carcinoma in 49 cases (14%). Sufficient material for cytologic examination was found in 343 cases. Of the 16 cases of T1a carcinoma in histologic examination, cytology found only 1, which was a G3 carcinoma. Of 33 T1b carcinoma in histologic examination, cytology found 6 and an additional 7 were suspect findings. Out of 6 G3 tumors in histologic examination, cytology showed 4. In our hands the proportion of false-negative cytologic findings in randomly taken FNA was so large that routine use of random FNA prior to TUR or as a screening procedure cannot be recommended, but positive FNA finding can be regarded as cancer.