Objective: To evaluate satisfaction and burden of mental health personnel providing mental health services for substance users and their families. Method: Five hundred twenty-seven mental health workers who provide treatment for substance users in five Brazilian states were interviewed. Data on sociodemographic characteristics and measures of satisfaction (SATIS-BR) and burden of mental health personnel (IMPACTO-BR) were collected. Results: Type of mental health service and educational attainment were associated with degree of satisfaction and burden. Therapeutic community workers and those with a primary education level reported being more satisfied with the treatment offered to patients, their engagement in service activities, and working conditions. Workers from psychosocial care centers, psychosocial care centers focused on alcohol and other drugs, and social care referral centers (both general and specialized), as well as workers with a higher education, reported feeling overburdened. Conclusion: This study offers important information regarding the relationship of mental health personnel with their work. Care providers within this sample reported an overall high level of job satisfaction, while perceived burden differed by type of service and educational attainment. To our knowledge, this is the first study with a sample of mental health professionals working with substance users across five Brazilian states.