Conformational restriction of previously disclosed acyclic diphenylethyl) diphenylacetamides led to the discovery of several potent inhibitors of acyl CoA: cholesterol acyltransferase (ACAT). cis-[2-(4-Hydroxyphenyl)-1-indanyl] diphenylacetamide (4a) was the most potent ACAT inhibitor identified (IC50= 0.04 μM in an in vitro rat hepatic microsomal ACAT assay, ED50= 0.72 mg/kg/day in cholesterol-fed hamsters).