Background. Long-term sick leave is one of the main risk factors for permanent exit out of the labour market. The longer the duration of sickness absence, the less likely sick leave conclusion. Objectives and Methods. The aims were to analyse possible determinants of sick leave conclusion and their relative impacts, to analyse the properties of two models for the assessment of sick leave conclusion, to study the impact of a multidisciplinary vocational intervention for sick leave conclusion in a high-risk group for long-term sick leave compared to a matched-control group, and to compare the patients’ own assessment on chance to sick leave conclusion within 6 months with the assessment of a team of rehabilitation professionals. A prospective cohort study of 943 patients aged 18 to 63 years, sickness certified at a Primary Health Care Centre in Sweden during 8 months in 2004, and follow-up for three years. Results. Significant determinants increasing time to sick leave conclusion were number of sick leave days the year before baseline, age and a psychiatric diagnosis (F in ICD-10). Concordance between actual sick leave conclusion and that predicted by a computer-based model was 73-76% during the first 28-180 days in a manual model, and approximately 10% units higher in a computer based model. Three nomograms provided detailed information on the probability on sick leave conclusion. Before intervention started, the rehabilitation group had a 73% higher sick leave conclusion rate than the control group but during the rehabilitation programme period, a 51% lower conclusion rate, and after there were no significant differences between the groups. The patients’ and the rehabilitation teams’ assessment scores were highly correlated (r=0.49).   Conclusions. Previous sick leave was the most influential variable associated with sick leave conclusion. A computer- based assessment model gave more detailed information on sick leave conclusion than a manual model. A multidisciplinary intervention declined sick leave in a high-risk group for long-term sick leave but after intervention there was no difference between groups. Patients’ own view on sick leave conclusion was highly correlated to the assessment of professionals’.