The prevalence of congenital heart disease (CHD) in Tibet has not been fully investigated. The aim of this study was to illustrate and compare the prevalence of symptomatic CHID and its major subtypes in Tibetan children at different altitudes. A total of 5,790 children from regions at altitudes of 3,500 to 4,100 m (group L) and 4,548 children from 4,200 to 4,900 m (group H) were compared for CHD prevalence. Group H had greater prevalence of total CHD (12.09 vs 4.32 per 1,000, p <0.001), patent ductus arteriosus (PDA, 7.70 vs 1.38 per 1,000, p <0.001), and atrial septal defect (ASD, 3.52 vs 2.25 per 1,000, p = 0.23) than group L. The differences were more remarkable in women (CHD, 18.63 vs 4.88 per 1,000, p <0.001; PDA, 11.53 vs 1.74 per 1,000, p <0.001; ASD, 5.32 vs 2.79 per 1,000, p = 0.15). No significant difference was observed in the prevalence of ventricular septal defect between the 2 groups (0.44 vs 0.35 per 1,000, p >0.05). The most common cardiac defect was ASD (52.0%) in group L compared with PDA (63.6%) in group H. In group L, women had slightly and insignificantly greater prevalence of total CHD, PDA, and ASD than men. In contrast, the prevalence was almost threefold greater in women than men in group H. In conclusion, the CHD prevalence and composition differed significantly between populations of school children living above and below 4,200 m. (C) 2013 Elsevier Inc. All rights reserved.