Objective: To assess the cognitive cost of work for military police officers in the state of Rio de Janeiro. Method: This is a cross-sectional study with a quantitative approach, carried out with 446 military police officers, of both sexes, distributed between non-commissioned officers and officers, in the 7th, 15th, 20th, 24th and 41st Military Police Battalions. An instrument was used to depict sociodemographic, work, lifestyle and health conditions and a scale for assessing the human cost of work, which analyses the demands of the job through physical, cognitive and affective costs. The data was organized, processed and analyzed using the Statistical Package for the Social Sciences (SPSS) software, version 13.1. Results: The cognitive cost had the highest means, with severe results (μ = 3.86; SD = 0.86), representing greater demands in relation to the human cost of work among military police officers in the state of Rio de Janeiro and significant associations in relation to obesity, cognitive alterations in attention and memory, age and hours of sleep. Conclusion: In assessing the human cost of work, the cognitive cost was the most demanding in the work context of the military police officers surveyed, presenting a serious risk of illness.