To evaluate digestion, absorption and postprandial lipemia of diverse fats before and after fish oil capsule therapy (with ethylester) 20 healthy volunteers were recruited. A significant increase (p less than 0.001) in fecal fat excretion after fish oil capsule therapy, as well as serious diarrhoea after fat loads with 100 g of fish oil was noted. It was found, that under fish oil fat loads the total triglyceride content of the mucosa was significantly (p less than 0.001) lower compared to butter fat loads. Decrease digestion and absorption of omega-3 fatty acids was postulated.