Atypical cribriform lesions on prostate needle biopsy specimens are rare and difficult to diagnose. Of 574 high-grade prostatic intraepithelial neoplasia (PIN) lesions on needle biopsy seen at our institution over 75 months, we identified 23 consult cases in which the differential diagnosis was cribriform high-grade PIN versus infiltrating cribriform carcinoma. Prebiopsy prostate-specific antigen (PSA) averaged 6.5 ng/mL (range, 0.3 to 37.3). A positive digital rectal examination (DRE) was present in 12 of 22 (55%) patients for whom information was available. Ordinary high-grade PIN was present elsewhere in the biopsy specimens in 32% of cases. The following architectural features of cribriform glands were evaluated: number (mean, 5; range, 1 to 21); largest size (mean, 0.5 mm; range, 0.1 to 1 mm); necrosis (14%); detached cribriform fragments (18%); stromal fibrosis (18%); and bilaterality (22%). Cytologically, there was cellular maturation toward the center of the cribriform glands (45%); identifiable basal cells on hematoxylin and eosin sections (36%); marked nuclear atypia (9%); and mitoses (23%). Nucleoli were not visible in 18% of cases, small in 36%, and prominent in 45%. With a mean follow-up of 13.8 months for those without progression (25.9 months' overall follow-up), a repeat biopsy diagnosis of cancer was seen in 10 of 22 men [by report: Gleason score (Gs) 4 (n = 1); Gs 6 (n = 3); Gs 7 (n = 4); Gs 9 (n = 2); three biopsy specimens showed ductal features]. An additional two men developed bone metastases without biopsy. Overall, 12 of 22 (55%) patients had cancer on follow-up (one patient lost to follow-up). Four clinicopathologic findings predicted carcinoma on follow-up: positive DRE (p = 0.02); positive transrectal ultrasound (p = 0.02); bilateral atypical cribriform glands (p = 0.02); and detached cribriform glands (p = 0.04).