Traumatic brain injury (TBI) has long been known as a cause of hypopituitarism, and it is characterized by a high prevalence of neuroendocrine abnormalities. Boxing, one of the most common combative sports, may also result in TBI. As far as we know, pituitary functions including GH status have not been investigated in boxers. Therefore, in this preliminary study, we have assessed the pituitary functions in boxers. Eleven actively competing or retired male boxers with a mean age of 38.0 +/- 3.6 yr and 7 age-, sex- and BMI-matched healthy non-boxing controls were included in the study. Biochemical and basal hormonal parameters including IGF-I levels were measured. To assess GH secretory status in boxers and healthy controls, GHRH (1 microg/kg)+GHRP-6 (1 microg/kg) test was performed. After GHRH+GHRP-6 test, mean peak GH level in boxers and in controls were 10.9 +/- 1.7 and 41.4 +/- 6.7 microg/l, respectively (p < 0.05). Peak GH levels in 5 (45%) boxers were found to be lower than 10 microg/l and considered as severe GH deficient. In the control group, mean IGF-1 levels (367 +/- 18.8 ng/ml) were significantly higher than that obtained in boxers (237 +/- 23.3 ng/dl) (p < 0.01). All the other pituitary hormones were normal including ADH as no signs and symptoms of diabetes insipidus. There was a significant negative correlation between peak GH levels and boxing duration, and between peak GH levels and number of bouts. In conclusion, we think that boxing is a cause of TBI, and GH deficiency is very common among boxers. Further studies including large number of boxers, both professional and amateur, are needed to clarify pituitary dysfunction in boxers.