The authors sought to determine whether the risk of congenital heart disease (CHD) was greater for the children of mothers who lived close to a hazardous waste site (HWS) than for those who lived farther away. All cases (n = 1283) of confirmed CHD, and a random sample of 2,292 controls, born in Dallas County, Texas, from 1979-1984 were linked with 276 HWSs present during the study. The authors ascertained locations of households and determined the distance to the nearest HWS. They obtained odds ratios (ORs) for CHD. A 20% increased risk for CHD was found in association with maternal residence within 1 mile of an HWS (OR = 1.2, 95% confidence interval = 1.1-1.4). The results of this study suggests that a statistically significant additional risk for CHD is associated with maternal proximity to an HWS.