3-ureido derivatives of 4-phenylcoumarin and 4-phenyl-2-quinolone were synthesized and evaluated for acyl-CoA: cholesterolacyltransferase (ACAT)-inhibitory activity. These derivatives inhibited rat intestinal ACAT with IC50 values at the 10(-8) to 10(-9) M level and were found to normalize plasma cholesterol levels in cholesterol-fed rats when administered as dietary admixtures.