Background: Mental disorders are an important public health problem because of their prevalence and the probability of long-term work disability. The incidence of sickness absence with mental disorders has increased between 1985 and 2000, but little is known about trends in recent years. This study investigated the incidence of sickness absence due to common mental disorders in the Netherlands from 2001 to 2007. Methods: Observational study in about 1 million employees, working in various economic sectors, representative for the Dutch workforce. Sickness absence episodes were medically certified by an occupational physician utmost in the fifth week of absence. The 12-month incidence of medically certified sickness absence was calculated for each year by dividing incident episodes by the number of employees. Sick days due to common mental disorders were computed as percentage of the total number of medically certified sick days. Results: The 12-month incidence of sickness absence due to common mental disorders was 2.2% in 2001, increased to 2.7% in 2004 and decreased thereafter to 2.0% in 2007. The percentage of sick days due to common mental disorders was highest in the education sector (39%) followed by financial services (31%) and health care (30%). Conclusions: In the Netherlands, the incidence of sickness absence with common mental disorders was highest in 2004 and has decreased since then probably because of changes in sick leave compensation, economic market position and company policies.