Introduction: Important role is attributed to genetic polymorphisms influencing enzymatic activity in folate metabolism. These inherited genetic variants may influence fetal growth and fetal hypotrophy development. The aim of the study was to investigate the connection of 401A>G polymorphism of methyleneterahydrofolate dehydrogenasegene (MTHFD1) with increased risk of fetal hypotrophy. Material and methods: To the study group 120 women who delivered children with fetal hypotrophy and to the control group 120 healthy women were enrolled. Study group was divided into subgroups according to gestational age at delivery (52 patients <37 weeks, 68 patients ≥37 weeks) and to the neonatal weight (31 mothers of newborns with birth weight <1500 g, 89 mothers of newborns with birth weight ≥1500 g). The genetic analysis was performed with the use of PCR/RFLP method. Results: We observed statistically higher occurrence of mutated 401A allele in hypotrophy group (401A: 27,1 vs. 18,8%, OR=1,61, p=0,02). At mothers who delivered hypotrophic children weighted more than 1500 g the presence of 401A allele was higher (28,7 vs. 18,8%, OR=1,74, p=0,01). Additionally in mothers who delivered hypotrophic children before 37 gestational week statistically higher frequency of 401A allele has been noted (31,7 vs. 18,8%, R=2,01, p=0,007). Conclusions: Our results indicated that mutated 401A allele of MTHFD1 gene is essential risk factor of fetal hypotrophy in population of Polish women. Appropriate folate supplementation could be particularly essential in women carriers the genetic polymorphism influencing the folate metabolism.