OBJECTIVE: To explore the factors related to doctors' assessments of incapacity to work (IW). MATERIAL: Two general practitioners and 49 men and 102 women aged 20-45 years with ongoing sick leave. METHODS: The doctors saw all the patients jointly and discussed their emotions afterwards. Mental status, psychosocial stress, pain behaviour, tender structures, mobility and self-rated inability to work were assessed. Finally, the doctors separately rated the degree (0-100%) of reduced capacity for vocational work (DRCW). The inter-rater agreement was measured by kappa statistics. Prevalence odds ratios (OR) with 95% confidence intervals (95% CI) for IW (75-100% DRCW) were calculated by logistic regression. RESULTS: The patients were immigrants working in service. All reported pain, 53.7% had much psychosocial stress, 74.8% said they were unable to work and 22.5% were depressed. We were often touched by their life stories. The women had many tender-structure locations and many men had restricted mobility. Two-thirds (67.5%) had pain behaviour. The kappa value on the DRCW was 0.73. A third of the men (38.8%) and 26.5% of the women were assessed as having IW. The raters disagreed only in a few cases. Depressed men or men with pain behaviour had high ORs for IW (OR 12.8, 95% CI 3.3-68.5 and OR 5.6, 95% CI 1.5-21.1, respectively) as did women with self-rated inability to work (OR 7.0; 95% CI 1.6-32.0). CONCLUSIONS: Factors not clearly related to function had determined doctors' assessments of IW.