To detect in children with tetralogy of Fallot (ToF) the prevalence of associated cardiac anomalies in syndromic and isolated cases, the additional cardiac defects of 150 consecutive patients with ToF (102 isolated and 48 syndromic cases) were evaluated by review of echocardiographic, angiocardiographic, and surgical reports. Syndromic patients were classified into groups with branchial arch defects, Down syndrome, and other genetic conditions. ToF is significantly associated with additional cardiac malformations in patients with branchial arch (11 of 21, p <0.01) and Down (10 of 20, p <0.0001) syndromes. The subarterial ventricular septal defect with deficiency of the infundibular septum (4 of 21, p <0.01) and the right aortic arch (6 of 21, p <0.05) were prevalent in patients with branchial arch syndromes, whereas atrioventricular canal (10 of 20, p <0.0001) was associated with ToF in patients with Down syndrome. Peculiar anatomic cardiac patterns are present in children with ToF and may alert the cardiologist to look at additional cardiac anomalies. Moreover, the presence of some associated cardiac anomalies may suggest careful clinical evaluation for genetic syndromes.