To assess the impact of concomitant depression on quality of life (QoL) and health service utilisation of patients with osteoarthritis (OA). Data were collected from 75 primary care practices in Germany. Totally, 1,250 patients were consecutively approached; 1,021 (81.7%) questionnaires were returned and analysed. Measures included sociodemographic data, the Arthritis Impact Measurement Scale (AIMS2-SF) and the Patient Health Questionnaire (PHQ-9) to assess depression. A PHQ-9 score > or = 15 was defined as reflecting depression. Patients with a depressive disorder achieved significantly (all P < 0.001) higher scores in all AIMS2-SF dimensions. They had more contacts to general practitioners (P < 0.01), orthopaedics (P < 0.01) and to providers of Complementary Alternative Medicine offered e.g. by healers. Concomitant depression aggravates the burden of OA significantly. This results in increased health service utilisation. Appropriate treatment of depression would appear not only to increase QoL but also to lower costs by decreasing health service utilisation.