Nonionic detergents were found to affect absorption of neutral lipid and cholesterol. The effects of these detergents were related to their physicochemical properties. The most effective detergents for producing an inhibition of lipid absorption were detergents containing 90% hydrophobic components. Hydrophilic detergents did not interfere with lipid absorption and in some cases, it was facilitated. Studies done over a period of one month demonstrate that addition of a hydrophobic detergent to a high fat-high cholesterol diet results in lower serum levels of cholesterol and triglyceride and prevents cholesterol accumulation in the liver of the rat. This effect was also associated with significant loss of body weight