The significance of perineural invasion in prostate needle biopsy specimens for predicting extraprostatic extension is controversial. We correlated the presence of perineural invasion in needle biopsy specimens from 340 men with the presence of extraprostatic extension in corresponding radical prostatectomy specimens. Perineural invasion was present in 57 biopsy specimens. The sensitivity of perineural invasion for predicting extraprostatic extension was 32%, the specificity 88%, and the positive predictive value 42%. Biopsy specimens with perineural invasion had significantly more core specimens involved with tumor and higher biopsy-determined Gleason scores than those without invasion. Biopsy specimens with perineural invasion were significantly more likely to show extraprostatic extension and Gleason scores were higher in the resection specimens than those without perineural invasion. Multivariate logistic regression analysis showed that perineural invasion remained an independent predictor of extraprostatic extension. However, in multivariate analysis, including preoperative serum prostate-specific antigen (PSA) for 173 of the patients, the only independent predictor of extraprostatic extension was PSA. While perineural invasion in biopsy specimens is a predictor of extraprostatic extension at resection that is independent of other histologic features, the positive predictive value is low and it is not an independent predictor when serum PSA is included.