The lowering of plasma cholesterol levels in patients with coronary heart disease has been known for some time to be beneficial. Recently, however, an unequivocal improvement in the survival time of patients with existing coronary heart disease has been demonstrated in the 4S-Scandinavian Simvastatin Survival Study (where cholesterol lowering was achieved with an HMGCoA reductase inhibitor). This new development adds impetus to the search for novel agents with an even greater hypocholesterolaemic effect that might afford further improvements in the treatment of coronary disease. In this respect the potential advantages of a drug which interrupts cholesterol biosynthesis at the squalene synthase (SQS) step have been vigorously pursued, leading to the identification of potent inhibitors in vitro. To date the most effective inhibitors of SQS in vivo are the polyanionic natural products (termed squalestatins or zaragozic acids) and the substituted bisphosphonates. Both of these inhibitor series have been reported to have poor oral bioavailability in animals or to display potentially toxic actions. Thus alternative series of inhibitors have been sought, and we report our discovery that substituted phenoxypropylamines (PPAs, 1) represent a new series of orally active SQS inhibitors.