A household interview survey of 2,582 adult members of the Kaiser-Permanente Medical Care Program of Oregon conducted in 1970-71 contained detailed questions about cigarette smoking patterns. Detailed, computerized medical records were maintained for all inpatient and outpatient care rendered between 1967 and 1974 to the 1,761 children of the interviewed sample. Adjusted for age, family size, socioeconomic status, and duration of Health Plan membership, children in non-smoking households used significantly more outpatient services than did children in smoking households, a relationship largely accounted for by their use of more preventive medical services than by children in smoking households. There were no significant differences in inpatient medical care use and outpatient care use for respiratory illness by children of smoking and non-smoking households.