Objective — The implementation of a simple methodology to estimate full costs of services provided by a public mental health centre. Setting. CPS (NHS Mental Centre) Ussl 35, Magenta, Lombardy Region. Method — To estimate full costs of 16 types of service we followed a two step procedure. The first step was to estimate all costs attributable to the CPS. In the second one, we allocated this estimate to each type of service provided. We attributed to the CPS the following cost items: personnel, utilities (telephone, electricity, water, heating and cleaning), land & building, transports (for services provided outside the clinic) and a share of general cost of the USSL to which the CPS belongs. Full cost of each service was then calculated on the base of the yearly number of services provided and the time spent by each health professional. Results — In 1995, the CPS provided 14, 562 services. Total costs amounted to L 1,356 million, and more than three quarters of this amount was attributable to the personnel working at the CPS. Unit costs ranged from L 5,300 (drug administration) to L 442,400 (family therapy involving two professionals for 90 minutes) The unit cost of psychiatric visits, psychologist consultations and nurse domiciliary visits were L 105,300, L 106,600 and L 78,000, respectively. Conclusions — This approach requires accessible data and is relatively simple to manage. Some refinements are required, especially to improve the methodology for the determination and the allocation of overheads. However, we are convinced that this cost accounting procedure provides acceptable estimates of the services provided by the CPS. These estimates suggest that charges to be used to fund NHS providers may be too low, especially if fee-for-service will be the main funding source.