Bile acid (acidic sterol) and neutral steroid excretion were determined in 15 patients, 5 with conventional ileostomy, 5 with continent ileostomy, and 5 with continent ileostomy and an ileal resection. Acidic sterol losses were normal in conventional ileostomy patients and not significantly increased in those with continent ileostomy alone. Bile acid excretion rates were significantly increased in patients with a continent ileostomy and an ileal resection. Neutral steroid excretion was similar in all groups and not different from normal. Deoxycholic acid was not detected in ileal effluent of patients with conventional ileostomy and less than 2% of neutral steroid excreted was in the form of bacterial metabolites of cholesterol. The same was true of 6 of the 10 patients with continent ileostomies; in the other 4 patients at least 10% of acidic or neutral steroids were excreted as secondary bile acids or as coprostanol. Modification of steroids was not related to ileal resection. Continent ileostomy was associated with a significant increase in percentage water content and a reduction in the pH of ileal effluent.