OBJECTIVE We tried to verify retrospectively, the clinical importance of a single microfocal prostate cancer at biopsy (as microscopic aspect of a group of 12 neoplastic glands 40x) in patients subsequently treated with radical prostatectomy (RP). MATERIALS AND METHODS from January 2008 to November 2010 we carried out 760 eight-core prostate biopsies for increased PSA in patients with a prostatic volume of d < or =40 cc. A total of 252 patients (33.15%) had a prostate cancer and out of them 17 (6.7%) had a microscopic prostate cancer--16 a single microscopic focus and a case 2 microscopic foci in two different specimens. PSA ranged 5 to 7.4 ng/ml (mean 6.2 ng/ml), age ranged 61 to 75 (mean 68.29), Gleason score was G6 in all cases; in 4 cases a microscopic focus of PIN3 was associated. RESULTS All patients had a RP and the pathologic stage was T2a in 4, T2b in 1, T2c in 9 (3 of these had microscopic PIN3 at biopsy) and T3a in 3 (including the one with 2 microscopic foci of prostate cancer on 2 different bioptic samples). Gleason was G6 in 12 cases and G7 in 5. DISCUSSION The single microscopic focus of prostate cancer has always raised diagnostic problems, in fact some authors report these patients have 30 to 90% of probability to have a significant prostatic cancer (volume > 0.5 mi) whereas other authors found an insignificant prostatic cancer in 30% of the patients with a single microscopic focus of prostate cancer. It is really very difficult to predict the extent of the tumor in these cases because the different parameters employed are not reliable. Our series, although very small, support the hypothesis that significant cancers are more frequently associated with a single microscopic focus of prostate cancer at biopsy (in fact 17 out of 17 patients had a significant cancer) and consequently we feel that it is more oncologically correct to choose an aggressive therapy in these cases (RP, radiotherapy or androgen deprivation according to the individual case) rather then a "wait and see" which could be less cautious.