Hospital statistics for episodes coded as adverse effects of medicinal agents' were used to study deliberate self-poisoning among people aged 12-20 years in the Oxford Region. Admission rates rose sharply from the age of 12 years, more so for females than males, up to the age of 16 years in females and 18 years in males. Analgesics, antipyretics and psychotropic drugs were the agents most commonly used by both sexes and accounted for three-quarters of all admissions. Admission rates varied from year to year, but increased overall between 1974 and 1979, notably among people under 16 years of age. Admissions for 'adverse effects of medicinal agents' accounted for 4.7 per cent of all general admissions among people aged 12-20 years.