We examined the effect of potato peptides (PPC) in rats fed a cholesterol-enriched diet, in comparison with two cholesterol-enriched diets containing soy peptides (SPC) or casein (CNC), and a cholesterolfree diet containing casein (CN) for 4 weeks. The serum non-high-density lipoprotein (HDL) cholesterol level was lower in the PPC-(-18.39%) and SPC-fed (-32.76%) groups (p ,0.05) than in the CNC-fed group at the end of the feeding period. The low-density lipoprotein receptor mRNA level in the PPC-fed group, and cholesterol 7a-hydroxylase and scavenger receptor class B type 1 mRNA levels in the SPC-fed group, were higher (p ,0.05) than in the CN-and CNC-fed groups. Faecal neutral sterol and caecal short-chain fatty acid concentrations in the PPC-and SPC-fed groups were higher (p ,0.05) than in the CN-and CNC-fed groups. The faecal total acidic sterol concentration was higher in the SPC-fed group than in the CN-and PPC-fed groups. Caecal anaerobe and Bifidobacterium populations were higher (p ,0.05) in the PPC-and SPC-fed groups than in the CN-fed group. This study suggests that potato peptides, as soy peptides, alter caecal fermentation and steroid absorption and reduce the serum non-HDL cholesterol level in rats fed cholesterol.