Objective: to identify the prevalence of stress at work among health professionals and associated factors. Methods: cross-sectional study, with health professionals from hospital sectors in cities in the North of Minas Gerais/Brazil. Questionnaires were used, including the Work Stress Scale. Analyzes were carried out, bivariate with Pearson's chi-square test and multiple Poisson regression with Wald's chi-square and Deviance test and with the magnitude of associations estimated through the prevalence ratio. Results: 469 professionals were surveyed, with a prevalence of 62.7% of stress at work, with a medium/high level of stress associated with a below average quality of life, 10 to 20 years of work in the health area, with a workload of more than 40 hours a week and the oncology sector. Conclusion: nursing professionals are the most susceptible to stress. Prevention measures should be taken to minimize mental disorders in health professionals and, consequently, the risk of care errors.