Introduction Brazilian public institutions have been passing through changes since the 90 s. These changes have included new management and work organisation methods that entail better productivity, faster work pace, employee downsizing, temporary contracts and outsourcing among others. As a result, the rates of physical and mental illness among public servants have increased. Thus, the objective of this study was to establish the profile of illness-related absence, defined as time off from work due to illness certified by a physician, among workers of a Brazilian state public university in the year of 2012.

Methods In this cross-sectional study, secondary data were extracted from the institution’s occupational medical examination systems and medical reports. Results have been reported as simple and cumulative frequencies, while associations were estimated by chi-square tests, and distribution differences determined by post-hoc Z tests with Bonferroni’s correction coefficient.

Result During the study period, 538 workers were on sick leave. These consisted of married females aged over 41 years. Most of them had been working on the university’s hospital for 11–30 years, holding intermediate level nursing positions, and had taken one sick leave. Of these, 11% undertook some sort of work readaptation. The most frequent causes for sick leaves, which lasted for up to 15 days, were mental/behavioural disorders, and osteomuscular and connective tissue diseases. Statistical analysis demonstrated that some sociodemographic characteristics, such as sex and age, and job characteristics, such as work unit and position, influenced the development of illness, which in turn influenced sick leave duration and work readaptation conditions.

Discussion Our results present the magnitude of the problem that illness-related absenteeism is to the public sector and can assist in planning preventive actions, prioritising the most vulnerable occupational groups.