Much has been learned about preventing and treating coronary heart disease (CHD) since publication of the National Cholesterol Education Program (NCEP) Adult Treatment Panel II (ATP II) guidelines in 1993. Even with the recent release of the ATP III guidelines, clinical decision making has become increasingly complex as a result of the tremendous volume of new data, and because many common patient types do not fit precisely into the defined risk categories. The case studies presented here illustrate how data from recent trials and the clinician's judgment should be weighed together in the decision to initiate cholesterol-lowering therapy in patients with borderline risk levels, as part of a strategy for primary and secondary prevention of CHD.