Objective: To investigate the congenital heart disease (CHD) found in association with an increased nuchal translucency (NT) at 11-14 weeks of gestation in chromosomally normal and abnormal fetuses. Methods: Patients referred from January 1998 until May 2007 with an increased NT (≥95th percentile) where CHD was diagnosed were included. Chromosome analysis, fetal and postnatal echocardiography were performed. A postmortem examination followed pregnancy termination when possible. Results: Major CHD was identified in 68 of 967 fetuses with an increased NT (median NT 4.8 mm, range 2.5-22 mm). Major CHD was found in 34 of 693 fetuses (4.9%) with a normal karyotype and increased NT (median 5.2 mm, range 2.5-9.6 mm). CHD frequency increased from 1.9%, with NT between 2.5 and 3.5 mm, to 27.7% when NT was ≥6.5 mm. Septal defects predominated (20%) when NT was ≤3.5 mm. With NT >3.5 mm an equal distribution of CHD types was seen. Major CHD was identified in 34 of the 274 fetuses with an abnormal karyotype and increased NT (median 4.2 mm, range 2.5-22 mm). Conclusions: A variety of CHD is associated with an increased NT in the first trimester of pregnancy. Conotruncal defects, branchial arch derivative defects, left and right obstructive lesions (inflow and outflow) and shunts were seen. Copyright © 2008 John Wiley & Sons, Ltd.