Background: Inulin is a non absorbable polysaccharide with prebiotic effects, whose influence on blood lipids or insulin sensitivity is not well known. Aim: To assess the effect of oral administration of inulin on lipid profile and insulin sensitivity in dyslipidemic obese subjects. Material and Methods: A clinical trial, double blind, randomized with placebo was carried out in 12 obese, hypertrygliceridemic and hypercholesterolemic subjects between 19 and 32 years old. The subjects were randomized to receive 7 g/day of inulin or placebo in the morning, during 4 weeks. Biochemical and metabolic profiles and euglycemic-hyperinsulinemic clamp technique for assessing insulin sensitivity, before and after pharmacological intervention were performed. Results: After inulin administration, there was a significant reduction of total cholesterol (248.7±30.5 and 194.3±39.8 mg/dL; p=0.028), low density lipoprotein (LDL), cholesterol (136.0±27.8 and 113.0±36.2 mg/dL; p= 0.028), very low density lipoproteins (VLDL) (45.9±18.5 and 31.6±7.2 mg/dL; p=0.046) and trygliceride concentrations (235.5±85.9 and 171.1±37.9 mg/dL; p=0.046). No effect of inulin on insulin sensitivity was observed. Conclusions: The oral inulin administration reduced total cholesterol, LDL cholesterol, VLDL and trygliceride levels in dyslipidemic and obese subjects, without modifications in the insulin sensitivity. (Rev Méd Chile 2003; 131: 597-604)