The omega-3 fatty acids are essential for human growth, development and well-being. Numerous studies have shown that a relatively high intake of the omega-3 fatty acids are beneficial in brain and visual development, psychiatric disorders, rheumatic disorders, inflammatory responses and cardiovascular disease. As an example, low levels of tissue omega-3 fatty acids are associated with a markedly higher rate of death from cardiac causes compared to patients with relatively high concentrations of the omega-3 fatty acids. Obese patients often have an unhealthy dietary intake and evidence of increased inflammatory processes. After a gastric bypass patients will have decreased absorption of fats from the gastrointestinal tract and may become fatty acid deficient. While gastric bypass may decrease death from cardiovascular disease in morbidly obese patients, cardiovascular disease is still the most common cause of death after a gastric bypass. There are numerous nutritional deficiencies which occur after gastric bypass and many of these are well documented. However, there are no data concerning the plasma and tissue levels of omega-3 fatty acids in morbidly obese patients either before or after operation.