In the Gleason grading system for prostatic cancer only the two most prevalent patterns are reported, although a third (tertiary) pattern grade may be present. We compared the pathologic stage of 227 radical prostatectomies with tertiary pattern 5 to the pathologic stage of 604 radical prostatectomies lacking a tertiary component. Gleason score 3 + 4 tumors with a tertiary pattern of 5 were more likely to present with higher stage disease than those Gleason score 3 + 4 tumors without a tertiary component (P = 0.012) and at a stage similar to Gleason score 3 + 5 tumors. Gleason score 4 + 3 tumors with a tertiary pattern of 5 were less likely to be organ-confined than Gleason score 4 + 3 tumors (P = 0.02) and less likely to have lymph node metastases than Gleason score 4 + 4 tumors (P = 0.027). However, Gleason score 4 + 4 with a tertiary pattern of 5 were indistinguishable from Gleason score 4 + 4 tumors. The relative effects of a tertiary pattern of 5 were greatest when the primary and secondary stages were low but become obscured by the already aggressive nature of advanced primary and secondary patterns. Therefore, except for very high-grade tumors, tertiary scoring of prostatic adenocarcinoma at radical prostatectomy should be reported as it has prognostic significance.