22q11 deletions in conotruncal anomalies. Two children are reported in whom conotruncal anomalies (truncus arteriosus communis, tetralogy of Fallot) were associated with chromosome 22q11 deletion. In both cases, which represent the first published cases in Hungary according to the knowledge of the author, deletions were suspected on the basis of phenotype termed Di George syndrome. Nowadays the role of molecular genetics is growing in the etiology of congenital heart defects and the chromosome 22q11 deletions constitute one of the most frequent genetic mutations associated with congenital heart defects. The author emphasizes that clinicians must know about this disease, and in case of suspicion they should request for molecular genetic investigation. 22q11 deletions have an important roles in the prognosis of congenital heart disease, in counseling and in the prenatal diagnosis as well.