The aim of this paper was to study some epidemiological aspects of the infection by Brucella abortus in risk occupational groups in the microregion of Araguaína, Tocantins. For antibody research, 645 serum samples were analyzed by the complement fixation test (CF). A 4.0% frequency was found (26/645) in patients' serum and among those 4.1% (23/551) were slaughterhouses employees and 8.1% (3/37) rural workers. Of the total positive samples, three (2.0%) were women and 23 (4.7%) men; ten (2.9%) were between the ages of 18 and 30, six (3.4%) between 31 and 40, and nine (8.0%) were above 41 years of age. Risk factors for brucellosis in the study groups were age, background (OR = 2.45; CI 95% = 0.98 to 6.10) and previous work conducted with production animals (OR 2.36; CI 95% = 0.95 to 6.02). It was concluded that the infection by Brucella abortus is found in some risk occupational groups in the microregion of Araguaína, Tocantins, and control and prophylactic measures must be implemented emphasizing risk factors identified in the study.