Objective: To study cholesterol absorption and excretion in ileostomy subjects with different intakes of saturated fat and dietary ®bre. Design: Short-term experimental study, with four controlled diets in repeated measurements. Setting: Out-patients at metabolic-ward kitchen. Subjects: Nine healthy volunteers with conventional ileostomy after colectomy because of ulcerative colitis. Interventions: Four diet periods, each of 3 days duration: high saturated fat and low dietary ®bre (STAND); reduced saturated fat (RESAT); high saturated fat and high ®bre (FATFIB); and reduced saturated fat and high ®bre (RESATFIB). Main outcome measures: Absorption of cholesterol, and ileal excretion of cholesterol, bile acids, fat and energy. Differences between diets evaluated with Friedman's two-way analysis of variance by rank sum with Bonferroni adjustment, and post hoc differences assessed by rank sum comparison. Results: RESAT and RESATFIB reduced fractional cholesterol absorption by 7% and 10%; RESATFIB and FATFIB increased net cholesterol excretion by 46% and 54% respectively. Further, RESATFIB increased net sterol excretion by 18%, all compared to STAND (P`0.05 for all). All three intervention diets contained more phytosterols than STAND (P`0.05), and the phytosterol content was inversely correlated to fractional cholesterol absorption (r 7 0.77, P`0.01). Conclusions: Current nutrition recommendations to reduce saturated fat and increase dietary ®bre affect sterol excretion additively. The effect on cholesterol absorption might be partly explained by the content of dietary plant sterols. Sponsorship: Supported by grants from the Gothenburg Medical Society, grant numbers 94a086 and 99a082, and by the University of Gothenburg.