The relations between pre- and perinatal risk factors and asthma were investigated using a case-control study of 262 African-American children aged 4-9 years, both asthmatic and nonasthmatic, all of whom resided in a poor urban area and received health care at a local hospital-based clinic. Risk factors were ascertained through review of obstetric, perinatal, and pediatric records. Asthmatic children had significantly lower birth weights and gestational ages than nonasthmatic children and were more likely to have required oxygen supplementation and positive pressure ventilation after birth than nonasthmatics (p < 0.05). The mothers of asthmatic children were more likely to have smoked during pregnancy (50% vs. 27%), to have gained less weight during pregnancy (26.3 pounds (11.9 kg) vs. 34.5 pounds (15.7 kg)), and to have had no prenatal care (12% vs. 2% ) than mothers of nonasthmatic children. Multiple logistic regression demonstrated that the strongest independent predictors of asthma were maternal history of asthma (adjusted odds ratio (OR) = 9,7), lack of prenatal care (OR = 4.7), history of bronchiolitis (OR = 4.7), positive pressure ventilation at birth (OR = 3.3), low maternal weight gain (<20 pounds (<9 kg)) (OR = 3.4), and maternal smoking during pregnancy (OR = 2.8). These data suggest that pre- and perinatal exposures may increase susceptibility to asthma in inner city children.