It was established by studies conducted in the 1980s and early 1990s that significant increases in basal metabolic rate and protein catabolism occur in the acute stages following severe head injury. These metabolic responses can rapidly result in malnutrition and can have significant effects on the patient's neurological recovery, immunity, and length of stay in intensive care. This paper reviews the randomized studies that have been conducted on early versus delayed feeding and on enteral versus parenteral nutrition to determine how best to manage the nutritional needs of severely head injured patients. There is insufficient evidence to advocate one route of feeding over the other, however, studies do indicate that, independent of the route, early adequate nutrition has more favourable outcomes particularly in relation to lower infection rates. The protein and caloric requirements of these patients should be based on their individual requirements as determined by their basal energy expenditure, urinary nitrogen balance and plasma protein levels. It is advocated that calories are replaced based on the patient's basal energy expenditure plus 20-40% and 2 g/kg of protein. Failure to make every attempt to meet the increased nutritional requirements of these patients puts them at risk of malnutrition with potentially detrimental consequences.