This study departed from a preconceived definition of VACTERL, including more than one of these six anomalies in the same infant: V (vertebral anomalies), A (anal atresia), C (congenital heart disease), TE (tracheoesophageal fistula or esophageal atresia), R (reno-urinary anomalies), and L (radial limb defect). Under this definition, 524 infants were ascertained by ECLAMC from almost 3,000,000 births examined from 1967 through 1990. Observed association rates among VACTERL components as well as between VACTERL and other defects were compared against randomly expected values obtained from 10,084 multiply malformed infants (casuistic method) from the same birth sample. Conclusions were: 1) Cardiac defects are not a part of VACTERL. 2) Single umbilical artery, ambiguous genitalia, abdominal wall defects, diaphragmatic hernia, and anomalies that are secondary to VACTERL components (intestinal and respiratory anomalies, and oligohydramnios sequence defects) are frequent enough to be considered an "extension" of VACTERL, and cardiac defects should be included in this category. 3) Neural tube defects are negatively associated with VACTERL which could not be explained by selection bias or any other operational artifact. High embryonic lethality or mutually exclusive pathogenetic mechanisms could be suitable explanations. 4) Results were not clear enough to determine whether VACTERL should be defined by at least two or three component defects.