Objective: The present study aims to investigate the risk of developing second primary prostate cancer after treating initial primary prostate cancer and to determine the role played by different variables including age, race, marital status, etc. regarding this risk. Materials and methods: We have conducted a retrospective cohort study to evaluate the risk of developing second primary prostate cancer. Data needed for this investigation was obtained from surveillance, epidemiology, and end results (SEER). Analysis of the risk of developing SPPC compared to the general population was obtained by measuring the standardized incidence ratios (SIRs). Results: Incidence of initial primary prostate cancer was more evident at 60-69 years of age, 38.84% (59,067) than different age groups. Marital status was found to have a significant impact on the incidence of prostate cancer. Married men (83.78% of the study sample) had a higher incidence of developing IPPC in comparison with single ones (p<0.001). Furthermore, the highest SIR values were noted in patients who were diagnosed with the local stage of prostate cancer in comparison with other stages (O/E 0.01, 95% confidence interval (0.01-0.02). Conclusions: The risk of developing second primary prostate cancer after treating the initial one is increased over time and is found to be the highest in old aged patients (60-69 years), who were diagnosed with initial primary distant stage prostate cancer of adenocarcinoma histologic type.