Prostatic intraepithelial neoplasia (PIN) is a putative premalignant change in the human prostate. Previously, the spatial association of PIN with invasive carcinoma has been described in the study of total prostatectomies. PIN is frequently recognized in prostate needle biopsy specimens in which no carcinoma is apparent. To further define the potential significance of PIN, we performed repeat ultrasound-guided prostate needle biopsy in 21 men who had PIN identified on prostate biopsy performed because of an abnormal finding on digital rectal examination. Twelve patients (57%) had carcinoma identified on their second procedure including all who had intermediate- and high-grade PIN on the initial procedure. Prostate-specific antigen correlated with PIN grade and carcinoma on the secondary procedure, although this did not achieve statistical significance. Men with PIN on prostate needle biopsy should undergo repeat sampling to exclude missed carcinoma.