Background despite an intensive focus on worker health over the last three decades, the prevalence of work-related diseases remain largely unchanged in denmark and internationally. in recent years, american and australian researchers have developed new approaches to integrate health promotion, prevention of work- related disease and organization of work. the aim of this study was to examine whether an integrated approach to health, wellbeing and productivity at work (itaspa) intervention would promote the mental health and wellbeing of workers. methods two worksites were recruited and offered the intervention and 76 cleaners agreed to participate in the scientific evaluation. at each worksite, employees developed initiatives to improve the psychosocial work environment, building on top of existing work environment programs, practices and procedures. the developed initiatives did not hold any physical activity components. the intervention was planned to run for 12 months, and this analysis presents data from the first of four follow-ups. data on mental health and wellbeing were obtained using the sf12 and orebro questionnaires. using a stepped wedge design, participants functioned as their own controls. data were analysed using a linear mixed model with random slope and intercept. intercorrelation of repeated measurements was included in the models as random effect. results the results showed significant decrease in sleeping problems (-4.04, 95% ci, -5,32- -2.75) after the intervention. moreover, there was a non-significant increase in the amount of time participants had felt relaxed and calm (0.33, 95% ci, -0.10- 0.96) and a small non-significant decrease in the amount of time participants had felt sad (-0.004, 95% ci, -0.42-0.41). finally, results showed a small non-significant increase in how much physical pain had challenged the daily work (0.04, 95% ci, -0.21-0.30). conclusion the findings show that itaspa intervention led to signifi- cantly reduced sleep problems. there was a tendency of improved self-ratings of feeling relaxed and calm as well as reduced feeling sadness. the intervention did not decrease ratings of whether physical pain challenged the daily work, however, the worksites decided to focus on the psychosocial