Authors report cytogenetic findings in 34 alive newborns presenting congenital malformations in the first week (Group A). These findings have been tested with Group B (100 malformated children up to 12 years old) and Group C (1,000 hospital patients of any age). Chromosomic anomalies in 44, 22 and 15% of the groups respectively are found. Performance of kariotype in any newborn with congenital malformations for detection of chromosomic aberrations or familial translocations in disbalance is needed.