PURPOSE: Gleason score(GS) 7 tumors contain patterns 3 and 4 in various proportions. The clinical and pathological characteristics of patients with GS 3+4 and GS 4+3 found during a radical prostatectomy(RP) were retrospectively evaluated. MATERIALS AND METHODS: 124 cases of GS 7 prostate cancer were identified between April 2004 and February 2006. None of these patients had received either preoperative hormonal therapy, including 5alpha-reductase inhibitors, or radiation therapy. After classifying patients with GS 7 tumors into those with GS 4+3 and GS 3+4 tumors, the two groups were compared according to various clinicopathological parameters. RESULTS: In total, 84(67.7%) and 40(32.3%) of patients had final GS of 3+4 and 4+3, respectively. A final GS of 4+3 was associated with a higher pre-biopsy level of prostate-specific antigen(p<0.001) and a higher biopsy Gleason sum(p<0.001). Also, a higher pathological T stage(p=0.005), tertiary Gleason pattern 5(p<0.001), seminal vesicle invasion(p=0.008), bladder neck invasion(p=0.002), angiolymphatic invasion(p=0.008), perineural invasion(p=0.045), positive surgical margins(p=0.038) and larger tumor volumes(p<0.001) were associated with GS of 4+3. CONCLUSIONS: Our results demonstrated that the statistically significant differences exist between GS 3+4 and 4+3 prostate cancers. Thus, GS 7 prostate cancers may be considered heterogeneous in their biological behaviors, and GS 7 prostate cancers with a GS of 4+3 may be considered more aggressive tumors compared to those with a GS of 3+4.