This study describes service utilisation under routine clinical activity and the costs of providing mental health care for 24 months for the whole population of 330 subjects who had first contact with the Magenta Community Mental Health Centre during one year. The mean age of patients was 42.5 years, and 61% were females. According to ICD 10 criteria, 7% were diagnosed as having schizophrenia, 22% mood disorders, 37% neurotic disorders, 15% personality disorders and 19% other diagnoses. The clinical routine activity was monitored for 24 months from the first contact for each patient. The mean cost for a schizophrenic patient is more than double that of other patients. In-patient activity and community services accounted, respectively, for 49.7% and 50.3% of the total costs. Total health care costs per patient differ widely according to whether patients had been hospitalised during the observation period. Patients with a previous psychiatric contact and a longer duration of illness were more costly than the other patients. Multiple regression analysis was used to assess the association between all the individual variables and costs. For the whole population, the model explains 50% of the cost variation. Higher treatment costs were positively associated with the presence of previous psychiatric contacts and referral to the CPS by other sources than a general practitioner, and negatively associated with age.