The National Health Interview Survey was administered in 1981 to a national probability sample of approximately 42,000 families. The questions on the Child Health Supplement of the survey were asked about one child in each family that had a child under age 18. The supplement included a series of questions about prescription and nonprescription medications and vitamin and mineral supplements. The respondents supplied information on 15,416 children under age 18. About two-thirds of the children had had some form of medication or vitamin-mineral supplement during any 2-week period in 1981. About one-third of the children were using medications that had been prescribed or recommended by a physician. About 17 percent of the children had been taking medication (excluding vitamin-mineral supplements) daily or nearly every day for the previous 3 months. Use of medications varied by age group. About one-fourth of the children 0-2 years were being given two or more physician-prescribed or -recommended medications or supplements. Use of medications was highest in the first quarter of the year.