BACKGROUND: Providing care for mental health problems concerns General Practitioners (GPs), Private Psychiatrists (PrPs) and Public Psychiatrists (PuPs). As patient distribution and patterns of practice among these professionals are not well known, a survey was planned prior to a re-organisation of mental health services in an area close to Paris METHODS: All GPs (n = 492), PrPs (n = 82) and PuPs (n = 78) in the South-Yvelines area in France were informed of the implementation of a local mental health program. Practitioners interested in taking part were invited to include prospectively all patients with mental health problem they saw over an 8-day period and to complete a 6-month retrospective questionnaire on their mental health practice. 180 GPs (36.6%), 45 PrPs (54.9%) and 63 PuPs (84.0%) responded. RESULTS: GPs and PrPs were very similar but very different from PuPs for the proportion of patients with anxious or depressive disorders (70% v. 65% v. 38%, p < .001), psychotic disorders (5% v. 7% v. 30%, p < .001), previous psychiatric hospitalization (22% v. 26 v. 61%, p < .001) and receiving disability allowance (16% v. 18% v. 52%, p < .001). GPs had fewer patients with long-standing psychiatric disorders than PrPs and PuPs (52%, 64% v. 63%, p < .001). Time-lapse between consultations was longest for GPs, intermediate for PuPs and shortest for PrPs (36 days v. 26 v. 18, p < .001). Access to care had been delayed longer for Psychiatrists (PrPs, PuPs) than for GPs (61% v. 53% v. 25%, p < .001). GPs and PuPs frequently felt a need for collaboration for their patients, PrPs rarely (42% v. 61%. v. 10%, p < .001).Satisfaction with mental health practice was low for all categories of physicians (42.6% encountered difficulties hospitalizing patients and 61.4% had patients they would prefer not to cater for). GPs more often reported unsatisfactory relationships with mental health professionals than did PrPs and PuPs (54% v. 15% v. 8%, p < .001). CONCLUSION: GP patients with mental health problems are very similar to patients of private psychiatrists; there is a lack of the collaboration felt to be necessary, because of psychiatrists' workload, and because GPs have specific needs in this respect. The "Yvelines-Sud Mental Health Network" has been created to enhance collaboration.