Abstract Purpose Employees with mental disorders (MDs) are more likely to exit the labour market prematurely. In Western European countries, characteristics of employees diagnosed with a MD have not been reported comprehensively, hampering targeting the risk group and developing preventive interventions. The aim was to describe the socio-demographic, health, treatment, organisation, job and labour market characteristics of employees diagnosed with a MD in Germany and their gender differences. Methods This cross-sectional study uses baseline data from sick-listed (≥6 weeks) employees diagnosed with a MD, aged 20-60 years, who were patients in the German mental health care, and recruited in the context of a return to work (RTW) intervention evaluation trial (RTW-PIA study). Descriptive T-tests/Chi-2 tests were applied. Results 484 individuals (58.5% female; 31% highly educated, average age 42.6) were included, of which 88.4% had affective disorders. Most were salaried employees working full-time, employed in large companies and having permanent contracts. 65.5% reported moderate depressions and the average work ability was 3.9 on a 0-10 scale. 74.2% had a positive RTW prognosis; 15.3% scored high levels of RTW self-efficacy. Gradual RTW (GRTW) was perceived the most important requirement for RTW (76.9%). More than 60% had discussed various work-related topics during therapy; further RTW-measures were prepared among 47.7%. Almost 60% received a recommendation for GRTW. Significant gender differences were found among the socio-demographic, health, job and labour market characteristics. Conclusions This study gives insights into a hardly investigated group. Almost two thirds had moderate depressions, 84.7% had low RTW self-efficacy and a very low average work ability. This highlights the vulnerability of persons with MDs in the labour market and suggest an urgent need for more work-related (health-)care. Gender differences need to be better addressed in mental health research. Key messages • Comprehensive knowledge of the characteristics of sick-listed employees diagnosed with MDs is crucial for targeting interventions to promote RTW. • Moderate depression scores, low RTW self-efficacy and very low work ability highlight the vulnerability of persons with MDs in the labour market, suggesting an urgent need for more work-related care.