Objectives: The objective of this study was to investigate the association of methylenetetrahydrofolate reductase (MTHFRc.677C>T)and methionine synthase reductase (MTRR c.66A>G) genetic polymorphisms with the occurrence of congenital heart disease (CHD) and its subtypes in children. The gene discussed is MTHFR; the disease is congenital heart disease.