BACKGROUND: Currently there are no widely applied methods which could identify, at the time of head trauma, those mild traumatic brain injury (mTBI) patients who later develop pituitary dysfunction. The effect of alcohol consumption on post-TBI endocrine dysfunction is unclear. METHODS: Five hundred and eight TBI patients, 406 of them with mTBI, were studied. Sixty-one patients (46 males, 15 females) were available for follow-up. Admission serum samples were evaluated for S100B protein and markers of alcohol consumption: ethanol level for day-of-injury intake and carbohydrate deficient transferrin (CDT) level for regular alcohol consumption. Regular alcohol consumption was defined as CDT > 1.5%, including both social and heavy drinkers. Admission and one-year follow-up samples were evaluated for pituitary dysfunction. RESULTS: Newly developed pituitary hormone deficiency was found in 16% of mTBI patients. When cohorts developing and not developing late pituitary dysfunction were compared, 30% and 69% of patients were regular alcohol consumers, respectively (p = 0.02). Neither S100B level nor day-of-injury alcohol consumption was predictive of late pituitary dysfunction. CONCLUSION: The findings of this preliminary study suggest that regular alcohol consumption may protect against the late endocrine consequences of mTBI. Alcohol intake during the weeks preceding mTBI may identify patients at higher risk for late pituitary dysfunction.