BACKGROUND: Collaborative care with a care manager in primary care improves care. OBJECTIVE: To study whether care manager support leads to improved work ability, decreased job strain and reduced time of sick leave among primary care patients with depression. METHODS: A clinical effectiveness study of care managers for depression patients seeking care in primary care was conducted in a RCT 2014 -2016. Patients in the intervention group were assigned a care manager. In the 12-month follow-up, patients with employment (n = 269; intervention n = 142, control n = 127) were studied concerning work ability, job strain and sick leave. RESULTS: An association was shown between reduction of depressive symptoms and improved work ability for the entire group. At 12-month follow-up a statistically significant difference of reduction of depressive symptoms was seen between the groups (MADRS-S: intervention 10.8 vs control 13.1, p = 0.05) as well as increased quality of life (EQ-5D: intervention 0.77 vs control 0.70, p = 0.04). In the intervention group, a concordance was found between the patient's prediction of return to work and the actual return to work (91%for intervention and 68 %for control group, p = 0.047). CONCLUSIONS: Compared to usual care, the care manager does not seem to further improve perception of work ability, job strain or perception of social support per se among the patients despite a long-term effect on depression symptoms. The lack of a long-term effect regarding these aspects may be due to the fact that care manager support was only provided during the first three months.