Objectives Since the 1980s, restructuring process of Brazilian economy promoted an increase in the tertiary sector. Since then, changes in the work-related diseases were observed. The impact of medical leaves due to chronic diseases, such as mental disorders, is a topic that deserves attention. The aim of this study is to determine the prevalence of long-term disabilities due to mental illness in the Brazilian adult worker population.

Methods This ecological study uses the 2009 database of the Brazilian Institute of Social Security. It is intended to collect data about social security benefits for long-term work-disability, that is, more than 15 days sickness absence. Inclusion criteria were diagnosis of disability listed in Chapter V (Mental and behavioural disorders) of International Classification of Diseases, 10th revision.

Results More than 2 million of benefits were granted in 2009. Mental disorders were the third leading cause of disability (about 9.3%). Among this group, work-related diseases were about 7% of the total number. In general, there is a sex similarity, but the urban population is more affected than rural. The most common diagnosis were “Reaction to severe stress, and adjustment disorders” and “Depressive episode”.

Conclusions Due to financial and emotional impact on all parties involved (the pension system, employers and employees), action plans should be implemented to minimise mental disability, as it brings social exclusion and affects productivity. A governmental agenda supporting mental research programs, promoting national discussions are of paramount importance to implement public policies for mental health promotion, prevention and rehabilitation programs.