Objective: Neurocognitive impairment (NCI) is a well-known complication of human immunodeficiency virus (HIV) infection and may be influenced by a number of psychological factors. We examined the relationship between NCI and mental health disorders, including posttraumatic stress disorder (PTSD), in a cohort of 189 active-duty and retired U.S. military men living with HIV. Methods: Participants completed selected modules of the Composite International Diagnostic Interview (CIDI) to ascertain the presence of PTSD, major depressive disorder, and other mental health diagnoses. We also obtained demographic data, including history of head trauma, via personal interview. NCI was assessed with a comprehensive battery of standardized neuropsychological tests. Results: The median age of study subjects was 36 years (interquartile range [IQR] 28 to 43) and median total years of education was 14 (IQR 12 to 16). NCI was diagnosed in 19% of subjects. Individuals with and without a history of PTSD were similar with respect to most HIV-related characteristics; however, the former were significantly more likely to have a prior acquired immunodeficiency syndrome (AIDS) diagnosis. In multivariate analysis, lifetime history of PTSD was independently associated with NCI (odds ration [OR] = 6.12; 95% confidence interval [CI] = 1.85, 20.27), while a history of head of trauma was negatively associated (OR = 0.37 95% CI = 0.15,0.92). Conclusions: Our findings demonstrate that PTSD is an important predictor of NCI in this U.S. military cohort. HIV-infected individuals with cognitive difficulties should be screened for mental health disorders, including PTSD, and prospective studies of the longitudinal relationship between PTSD and NCI, as well as the impact of PTSD treatment on future NCI, are warranted.