Military sexual trauma (MST) is linked to a range of deleterious health outcomes. Extant literature has focused disproportionately on mental health sequelae of MST. Research is needed to better understand the extent to which MST contributes to alcohol misuse and related problems - key issues facing service members. Additionally, sex differences in the nature and prevalence of MST may impact sequelae. The present research examined (a) the prevalence of an MST history among female and male service members, (b) relations between MST history and risk for alcohol misuse and related problems, and (c) potential sex differences in these experiences and outcomes. Data from current and previous service members (334 males and 70 females) were drawn from Operation: SAFETY (Soldiers and Families Excelling Through the Years), a longitudinal study of U.S. Army Reserve and National Guard (USAR/NG) soldiers and their partners. Analyses examined the prevalence and types of MST experienced, relations between MST history and three alcohol-related variables (total consumption, heavy drinking frequency, and alcohol-related problems), and differences by sex. Approximately one-third (33.7%) of service members reported an MST history. Females (61.4%) reported an MST history at more than twice the rate of males (27.8%). Interactions between MST and sex were significant for all alcohol-related variables. Among males, an MST history was related to 70% higher alcohol consumption, 86% higher heavy drinking frequency, and 45% higher alcohol problem scores. An MST history was unrelated to alcohol-related variables among females. Findings suggest a higher prevalence of MST among USAR/NG service members than is often reported in the literature, particularly among males. An MST history was associated with higher and more hazardous/harmful current alcohol consumption among male service members, highlighting the need for greater screening, prevention, and intervention among a population already at high risk for problematic alcohol use. Results underscore that MST is an important and prevalent experience requiring greater study alongside more traditional notions of service-connected trauma.