Numerous health consequences of children's exposure to maternal smoking have been demonstrated, including increased rates of low birth weight, infant mortality, respiratory infections, asthma, and modest impairments of cognitive development. There is little evidence, however, linking maternal smoking and increased rates of children's behavior problems. Data from the population-based National Longitudinal Survey of Youth were used to investigate the possible association of maternal smoking and behavior problems among 2256 children aged 4 through 11 years. In multiple regression analyses the authors controlled for child's race, age, sex, birth weight, and chronic asthma; family structure, income, and divorce or separation in the prior 2 years; mother's education, intelligence, self-esteem, employment status, chronic disabling health conditions, and use of alcohol during pregnancy; and the quality of the home environment as assessed by the Home Observation for Measurement of the Environment-Short Form to investigate the relationship between maternal smoking and children's behavior problems. The measure of maternal smoking status reflected two levels of smoking intensity (less than a pack per day and a pack or more per day) for each of three different categories of children's exposure: prenatal only (mother smoked only during pregnancy), passive only (mother smoked only after pregnancy), and prenatal plus passive exposure (mother smoked both during and after pregnancy). Measures of children's behavior problems included the overall score on a 32-item parent-reported child Behavior Problem Index (PBI), scores on the BPI's subscales, and rates of extreme scores on the BPI.(ABSTRACT TRUNCATED AT 250 WORDS)