BACKGROUND: Doctor-shopping may reflect unmet patient needs and places a significant burden on health resources; however little is known about its underlying reasons and how it relates to mental illness and its recognition in an open access fee-for-service setting. METHODS: In 2003-2004, consecutive patients of 46 French general practitioners (GPs), completed in the waiting room the self-report Patient Health Questionnaire and reported on service use in the past six months. During the consultation, GPs rated the severity of any physical and psychiatric disorders. RESULTS: Of 1079 patients, those rated by the GP as having a common mental disorder were significantly more likely to be doctor-shoppers but only if visiting another GP because of dissatisfaction with previous care (OR=2.3, 95% CI: 1.4-3.7). A similar trend is observed for those identified as having a common mental disorder by the Patient Health Questionnaire. Among patients with a common mental disorder, 'dissatisfied' doctor-shoppers were significantly more likely to be recognised as cases by the GP, adjusting for covariates (OR=6, 95% CI: 2.1-17.2). This was not the case for those doctor-shopping for practical reasons alone. CONCLUSION: Doctor-shopping behaviour is associated with higher rates of mental illness and, among cases, an increased likelihood of recognition by the GP, only however for doctor-shoppers dissatisfied with previous care. This suggests a benefit to letting patients choose their GP as is the case in France and change if not satisfied.