The incidence and spectrum of extracardiac malformations in congenital asplenia syndrome were determined by review of43 cases (40 live-births) identified in the province of British Columbia over a 21 year period. Major extracardiac anomalies (excluding those of abnormal arrangement of the organs) were identified in nine cases (21%), and minor anomalies were present in an additional twelve infants (28%). Extracardiac anomalies were associated with one spontaneous stillbirth, one termination of pregnancy, and two early neonatal deaths. In an additional four newborns, they contributed to a decision not to palliate the complex cardiac anomalies. Gastrointestinal malformations led to neonatal intestinal obstruction in four infants. Of the 14 surviving children, one is severely handicapped due to a congenital anomaly of the central nervous system. The clinical significance of extracardiac malformations and their developmental implications are discussed.