Data reflecting the clientele of the Child and Adolescent Psychiatric Service of the Canton of Zurich (Switzerland) spanning two decades between 1973 and 1993 were analyzed. Referral patterns, age distribution, sex ratio in relation to age, and family background are reported on. In addition, the distributions of diagnoses according to ICD-9 and ICD-10, respectively, are compared. Furthermore, four main types of child and adolescent psychiatric disorders are documented with regard to age distribution. Finally, abnormal psychosocial situations according to the multiaxial scheme of classification are reported.