Neurologic diseases or neurologic complications of medical diseases accounted for 17% of all admissions to an adolescent service over a 2½-year period. The largest diagnostic categories were trauma, convulsive disorders, infectious and parainfectious illness, and drug ingestion or abuse. Of all the patients admitted, 62% were suffering acute and potentially fully reversible illnesses, 23% suffered from chronically handicapping conditions, and 15% had progressive and potentially or probably fatal diseases. These illnesses account for a significant proportion of the morbidity and mortality of the adolescent years. In addition, many of these conditions superimpose chronic disabilities upon attempts at full adult adjustment. The effect of these illnesses on the patient's life adjustment calls for a multidisciplinary approach to treatment, with the full availability of a wide range of ancillary personnel.