Human intestinal specificity toward sterols was studied by a balance method in 10 hyperlipoproteinemic patients fed plant sterol mixture with chromium sesquioxide as fecal flow marker. The mean fecal recovery of campesterol (C28) was 20 % less than that of β-sitosterol (C29). This difference persisted when corrected for fecal flow (by marker recovery), indicating differences in their intestinal uptake (C28 > C29). The ratio of fecal cholesterol to its 5β-reduction products was lower than that of β-sitosterol in all patients; in vitro, 5β-reduction of both sterols was similar. The recovery of sterols from patients was unrelated to their 5β-reduction in the intestine. In sterol balance studies it is essential to measure cholesterol and plant sterols in the diet and to differentiate cholesterol and its transformation products from plant sterols and their products (Subbiah, 1972). Previous studies