Objective: to investigate the prevalence of negative self-rated health and associated factors among municipal health service workers in Diamantina, MG, Brazil. Methods: this was a cross-sectional census study using Poisson regression. Results: 203 health workers took part in the study, 70.9% were female, and 57.1% were up to 38 years old; prevalence of negative self-rated health was 28.6% (95%CI22.4;34.8); in the multivariate analysis, the following were associated with the outcome: being 39 years old or more (PR=1.56-95%CI1.01;2.40), monthly family income >3 minimum wages (PR=0.63-95%CI0.41;0.97), having another paid occupation (PR=0.55-95%CI0.34;0.89), poor sleep quality (PR=1.99-95%CI1.32;2.99), diagnosis of one disease (PR=2.33-95%CI1.13;4.81) or multiple diseases (PR=2.63-95%CI1.32;5.24), suffering aggression at work (PR=1.92-95%CI1.29;2.85), and frequent participation in domestic activities (PR=0.55-95%CI0.38;0.80). Conclusion: prevalence of negative self-rated health was high and was associated with sociodemographic, occupational, behavioral and health situation factors.