To determine the prevalence of pituitary hormone deficiencies after moderate traumatic brain injury (TBI). We conducted a prospective cohort and included 75 patients with moderate TBI with GCS between 9 and 13 who referred to emergency department of Shariati Hospital, Tehran/Iran, during 2004-2007. Pituitary hormones were assessed 3 and 6 months after injury. In 3(rd) month post-injury, 39 cases had not any pituitary dysfunction; however, deficiencies in one, two and three of the pituitary hormones were found in 26, 8 and 2 patients, respectively. Twenty one patients showed a deficiency in one of the pituitary hormones and only one case with deficiency of two after 6 months. The most prevalent changes occur in IGF-1 and LH/FSH after moderate TBI. However, the whole deficiencies decrease over the time.