Purpose: We analyzed the risk of dying of a second cancer after radical prostatectomy for clinically localized prostate cancer. Materials and Methods: We studied 1,910 patients who consecutively underwent radical prostatectomy between 1992 and 2004. These patients had a median age of 65 years, a median prostate specific antigen of 7.6 ng/ml and a median followup of 5.9 years. Overall disease specific, comorbid, second cancer specific and other mortality data were used as study end points in competing risk analyses. Fatal second cancers were subdivided into 10 categories. The numbers of observed deaths from second cancers were compared with expected rates using cancer registry data. Results: The risk of dying of a second cancer within 10 years after radical prostatectomy was 4.1%. This death rate was lower than that of comorbidity (5.8%) and prostate cancer (5.4%). Among second cancers colorectal cancer (0.74%), lung cancer (0.69%) and lymphoma, myeloma or leukemia (0.66%) were the most common causes of death after 10 years. Whereas the mortality rates from the other second cancers were within the expected range, fatal lung cancer occurred significantly less frequently than expected. Conclusions: The low probability of dying of a second malignancy within 10 years after surgery (about 4%) and the nevertheless relatively large contribution of second cancers to competing mortality (about 40%) reflect the good general health status of men selected for radical prostatectomy.