Bile acid binding resins are indicated for treatment of elevated plasma low-density lipoprotein cholesterol concentrations. In normoglyceridemic patients, plasma concentrations of low-density lipoprotein cholesterol and total cholesterol are closely linked, and for this reason resin treatment of elevated total cholesterol levels in these patients is rational and warranted. Hypertriglyceridemic patients may also have elevated total cholesterol concentrations, and several such patients have been treated with resin. However, resin therapy in these patients is hazardous, since the elevated cholesterol level mainly results from increased plasma concentrations of very-low-density lipoproteins or chylomicrons rather than low-density lipoproteins. In these patients, resin treatment has either no effect or an adverse effect on plasma triglyceride and cholesterol concentrations. The data presented show that fewer than 5 percent of patients whose total plasma triglyceride concentration exceeded 500 mg/dl had elevated low-density lipoprotein cholesterol concentrations, irre-spective of total plasma cholesterol concentrations, and no patient whose plasma triglyceride concentration exceeded 1,000 mg/dl had elevated low-density lipoprotein cholesterol levels. Treatment with bile acid binding resins in hypercholesterolemic patients is contraindicated in the presence of hypertriglyceridemia.