INTRODUCTION: Military service members are at risk of heat stroke, particularly due to physical exertion during training and tasks. Due to the serious nature and potentially fatal consequences of heat stroke, it is important to understand trends over time and among subgroups of service members in diagnoses of heat stroke. We aimed to replicate and extend recent work by Williams and Oh1 by examining the incidence of heat stroke in military service members from 2016 to 2021 and performing subgroup comparisons for sex, age, race, marital status, pay grade, and service branch. MATERIALS AND METHODS: Data were obtained from the Defense Medical Epidemiology Database (DMED). Incidence rates were calculated per 10,000 between 2016 and 2021. Single-sample chi-square analyses were used to examine trends related to heat stroke in subgroups relative to their group's population density within the military. RESULTS: Findings revealed that incidence rates for heat strokes declined by 5.46% in the study period. The total number of heat stroke cases between 2016 and 2021 was 2,295. Single sample chi-square analyses revealed overrepresentation in heat stroke diagnoses for male, younger, un-married, and White service members, for those in the Army and Marine Corps, and for those in junior paygrades, compared to what would be expected based on their population density within the military. CONCLUSION: Incidence rates of heat stroke among military service members declined from 2016 to 2021. Subgroups overrepresented in incidence rates likely reflect differences in training, tasks, and supervision. These results highlight the importance of ongoing attention to policies designed to prevent, recognize, and properly treat heat stroke in military settings.