In this study the effects of maternal folic acid (FA) supplementation on intestinal morphology and gene expressions relating to cell apoptosis and DNA repair of the intestine in intrauterine growth retarded (IUGR) and normal body weight (NBW) piglets were investigated. Twenty-four Yorkshire gilts were randomly allotted to a Control diet (1.8 mg FA per kg) or FA supplemented diet (30.3 mg FA per kg) during pregnancy. The expression of genes encoding DNA methyltransferase-1 (DNMT-1), genes related to cell apoptosis (p53, Bcl-2 and Bax) and genes involved in DNA repair (Mpg, Apex1 and Tdg, firstly cloned in the present study) were investigated by reverse transcription (RT)-PCR in the jejunal section of the intestine. Morphological analysis of middle section of intestine revealed a decreased intestinal development in IUGR piglets characterised by mucosal atrophy and decreased villus height compared with NBW piglets regardless of FA supplementation. The expression of p53, Bax, Mpg and Apex-1 was higher, but expression of DNMT-1 and Bcl-2 was significantly lower in jejunum of IUGR piglets compared with NBW piglets. Maternal FA supplementation could dramatically increase DNMT-1 and Bcl-2 expression, and decrease p53, Bax, Mpg and Apex-1 expression in the jejunum section of IUGR piglets. IUGR impaired intestinal development and apoptosis-related gene expressions in piglets, but maternal FA supplementation could improve the apoptosis-related gene expression of jejunum section of intestine.