Burnout Syndrome is a reaction to chronic stress in the workplace and causes harm to both the individual and the organization in which he is inserted. It can affect professionals from various sectors, impacting mental health and worker performance. Thus, it is important to have measures capable of assessing burnout symptoms in different occupational groups. The aim of this research was to look for evidence of validity based on the internal structure and relationship with external variables of the Burnout at Work Inventory (IBT) in a sample of Brazilian military pilots. The sample consisted of 259 military pilots (98.1 per cent men) from all regions of Brazil. Confirmatory factor analyzes were conducted to verify the plausibility of different factor structures of the instrument: one-dimensional, three-dimensional and a second-order model. The three-dimensional model and the second-order model presented satisfactory adjustment indices (CFI equal 0.956; TLI equal 0.951; RMSEA equal 0.090 (0.083 - 0.097)). The factor loadings were also satisfactory, ranging from 0.657 to 0.958. In addition, burnout scores showed a strong and positive relationship with the variables neuroticism, anxiety, stress and depression and a strong and negative correlation with engagement and job satisfaction. It can be concluded that IBT is a reliable measure for the evaluation of burnout in Brazilian military pilots.