The aim of the study was to prospectively assess the role of apical soft tissue biopsies in radical perineal prostatectomy (RPP) patients with documented apical prostate cancer (PCA) involvement. Between June 1998 and May 1999, 77 consecutive men with localized PCA and documented invasion of the prostatic apex underwent RPP by a single surgeon. Soft tissue biopsies were systematically obtained from the prostatic fossa overlying the apex at the time of surgery. Time to biochemical failure was calculated using the Kaplan-Meier method. The rates of positive apical margins and positive apical soft tissue biopsies were 23.4% (18/77) and 15.6% (12/77). The sensitivity, specificity and positive predictive value of positive apical margins for residual apical disease as determined by apical soft tissue biopsy were 41.7, 80, and 28%, respectively. The overall biochemical failure rate was 28.6% (22/77) with a median follow-up of 51 months (range 3-73 months). The 36-month biochemical recurrence-free survival rate was 55.9+/-14.9% for patients with positive apical biopsies and 78.7+/-5.3% for those with negative biopsies (P=0.023). In conclusion, positive apical soft tissue biopsy is an independent predictor of biochemical failure in patients with apical PCA who undergo RPP. Positive apical surgical margins poorly predict residual apical disease that is frequently identifiable by apical soft tissue biopsy. Apical soft tissue biopsies should therefore be obtained in patients with known extensive apical cancer involvement at the time of RPP.