The consequences of pregnancies in untreated phenylketonuria (PKU) mothers are a high incidence of spontaneous abortion, intrauterine growth retardation with microcephaly, congenital malformations, and abnormal intellectual development. PKU fathers, on the other hand, produce normal children. Obviously children of PKU women and men are at least heterozygous, proving that the abnormalities produced by the PKU mothers are not genetic but "intrauterinely environmental." Exposure to the mother's metabolic abnormalities affects the fetus during the entire pregnancy. A PKU mother can produce a healthy infant if she maintains a very restricted and controlled diet before and during pregnancy. However, even the most recent reports describe a very high incidence of congenitally abnormal children of PKU mothers, hence dietary compliance is not working in all cases. A 26-year-old PKU patient with proven fertility underwent standard ovarian stimulation in preparation for oocyte retrieval. Following conventional co-incubation of the oocytes and her husband's sperm, two embryos were transferred to the gestational carrier's uterine cavity, resulting in a single intrauterine pregnancy. Birth was induced at 39 weeks of gestation. The male infant weighed 3486 g. Head circumference was 36 cm and length 50.5 cm; there was no evidence of any abnormality and/or malformation. At 1 year of age, the child's growth measurements and development assessments were normal. This describes the first reported successful term pregnancy of an untreated PKU mother with the help of a gestational carrier (GC), producing a normal infant. This is an alternative method that should be offered to PKU women who are unable and/or unwilling to maintain a well controlled diet before and during pregnancy.