Prognosis for intermediate-risk prostate cancer (PCa) remains variable; therefore, we aimed to investigate high-risk factors for biochemical recurrence (BCR), and intermediate-risk PCa using radical prostatectomy to identify patients having equivalent BCR-free survival rates when compared to high-risk PCa. A total of 441 medical records were analyzed, including those of 169 intermediate-risk and 272 high-risk PCa patients. Risk factors for time to BCR were tested and analyzed using Kaplan-Meier survival analysis, log-rank tests, and Cox proportion hazards models. In the intermediate-risk group, prostate-specific antigen density (PSAD) and primary Gleason pattern were significant preoperative risk factors for BCR. Moreover, BCR-free survival of patients in the intermediate-risk group with a higher PSAD (>0.5 ng/mL/cm3) was comparable with that of patients in the high-risk group (P=0.735). When combining primary Gleason pattern 4 and 3 with PSAD cut-offs 0.3-0.7 ng/mL/cm3, we found that BCR-free survival of patients in the intermediate-risk group with a primary Gleason pattern 4 and PSAD >0.3 ng/mL/cm3 was comparable with that of patients in the high-risk group (P=0.463). PSAD and primary Gleason pattern are potential risk factors associated with biochemical failure in intermediate-risk PCa patients after radical prostatectomy. Regarding significant differences in prognosis according to PSAD as well as primary Gleason pattern on biopsy, a subset of the intermediate-risk patients could be identified with outcomes that were equivalent to that of high-risk patients.