We have studied the effect of polymeric cholesterol-free enteral nutrition (EN) on serum lipid and apolipoprotein levels in 30 consecutive non-diabetic, non-hyperlipaemic gastrointestinal patients. EN-40 +/- (SEM) 2 kcal/kg/day including 35% vegetable lipids (50% highly polyunsaturated fat, 50% medium chain triglycerides)-was delivered continuously (24h) via the gastric route for at least 2 weeks (mean duration: 35 +/- 4 days). In the entire group, serum total cholesterol decreased by 10.5% (p < 0.01) on day 7 and 17.5% (p < 0.01) on day 28 (n = 12); this was accompanied by 21% and 20% decreases in LDL-cholesterol and apolipoprotein B (p < 0.05) levels respectively, on day 28. In the 19 patients who were normocholesterolaemic on day 0, serum total cholesterol decreased by 15% (p < 0.01) on day 7 and by 28% (p < 0.05) on day 28 (n = 7). Conversely, in the other 11 patients with a low (<3.7 mmol/L) pre-EN serum total cholesterol level, no significant changes were observed during EN. We conclude that continuous, cholesterol-free EN has, in normocholesterolaemic patients, a marked cholesterol-lowering effect; the respective role of the composition of the diet and the continuous delivery of nutrient within the gut have yet to be investigated.