We have evaluated the signal and the volume of anterior pituitary, posterior pituitary and thyroid gland in preterm and term infants on MRI by using 3D T1-PETRA sequence. Our study showed that the intensity of anterior pituitary was positively correlated with gestational age (GA), negatively correlated with chronological age (CA). We showed the intensity of posterior pituitary was also positively correlated with GA, negatively correlated with CA. We also demonstrated that the intensity of thyroid was positively correlated with GA, negatively correlated with CA. Our results may have relation to the maturity of hypothalamic-pituitary-thyroid (HPT) axis.