The Authors analyze the activity of Pavia's General Hospital Psychiatric Unit over a ten year period. Data, presented as rates standardized by sex and age, are processed according to patients' residential socio-health districts. The analysis of the results shows marked differences in the Service utilization among different districts. Correlations between these differences and some socio-demographic and clinical variables enable the Authors to put forward some hypotheses in order to understand this pattern of Service utilization. In particular, "high-users" and patients with a past history of admissions to psychiatric hospitals tend to be found especially in the districts which provide the Service with a heavy workload. A closer attention to these patients and to their pathways to care will enable the Service staff to optimize its supply of care and to plan new kinds of treatments.