Esophageal atresia or tracheoesophageal fistula (EA/TEF) often occurs in association with a well-defined group of other anomalies. We report the prevalence of malrotation and other intestinal anomalies in a large data series comprising 632 nontrisomic infants with EA/TEF ascertained by the California Birth Defects Monitoring Program from January 1, 1983 to December 31, 1994. Consistent with findings reported previously in smaller case series, our findings showed a notable prevalence of imperforate anus (9.0%) and duodenal atresia (5.2%), among other gastrointestinal defects. They also showed a previously unrecognized high prevalence of intestinal malrotation (4.4%). Compared with other infants studied, the infants with EA/ TEF and malrotation of the intestine had a higher proportion of other associated anomalies (in particular intestinal, central nervous system, vertebral and rib, renal and genital anomalies). These findings indicate that intestinal malrotation is more common in infants with EA/TEF than is generally perceived, and that intestinal malrotation in an infant with EA/TEF is associated with a higher burden of additional congenital anomalies, suggesting that this group of infants may have more pervasive developmental deficits and poorer prognosis than has previously been recognized. Teratology 60:114-116, 1999. 1999 Wiley-Liss, Inc.