Attentional behavior was examined in one hundred twenty-six 72-month-old children for whom prenatal exposure to marihuana, cigarettes, and alcohol has previously been ascertained. Discriminant Function Analysis revealed a dose-response association between prenatal cigarette exposure and impulsive behavior as manifest on poorer performance on a response inhibition task and increased errors of commission on a sustained vigilance task. Performance on a series of memory tasks particularly those requiring verbal recall was also negatively associated with maternal cigarette use. Prenatal marihuana habits were associated with increased omission errors in the vigilance task, possibly reflecting a deficit in sustained attention. In addition, Discriminant Function Analysis revealed a dose-response relationship between prenatal marihuana use and a higher rating by the mothers on an impulsive/hyperactive scale. Relatively low levels of maternal alcohol consumption was related to decreased impulsive responding both in the response inhibition task and in terms of the mothers' perception of the child's behavior. The multifaceted approach of examining attentional behavior was essential to reveal the differential associations with the three prenatally used drugs. The implications of the observations and how the findings relate to and extend the existing literature is discussed.