US enlisted Marines have experienced a substantial increase in suicide rates. We sought to identify risk factors for suicide completions among male Marines who entered basic training in San Diego, California, between June 2001 and October 2010. Suicides that occurred during active-duty military service were counted from June 1, 2001, through June 30, 2012. A total of 108,930 male Marines (66,286 deployers and 42,644 never deployed) were followed for 467,857 person-years of active-duty service time. Of the 790 deaths, 123 (15.6%) were suicides. In the final multivariate hazard model, preservice characteristics of not being a high-school graduate (hazard ratio (HR) = 2.17, 95% confidence interval (CI): 1.28, 3.68) and being a smoker at the time of enlistment (HR = 1.91, 95% CI: 1.32, 2.76) were significantly associated with a higher risk for suicide completion. Diagnosed with traumatic brain injury (HR = 4.09, 95% CI: 2.08, 8.05), diagnosed with depression (HR = 2.36, 95% CI: 1.22, 4.58), and received relationship counseling (HR = 3.71, 95% CI: 1.44, 9.54) during military service were significant risks for suicide death. Deployment alone was not significantly associated with a risk for suicide death (HR = 0.53, 95% CI: 0.26, 1.05).