Two patients with heterozygous familial type 2 hypercholesterolemia are reported upon following treatment with end-to-side portacaval shunting. In both, the portacaval shunt decreased the cholesterol level by about 40 per cent. No adverse effects of the operation could be seen in either patient at 30 months, and no return of cardiovascular disease is evident in either patient. In one patient with large xanthelasmas, the lesions became a much duller yellow color and regressed from an elevated to flat appearance. However, the margins of the lesions did not change significantly. In young patients with heterozygous type 2 hypercholesterolemia in whom cardiovascular complications pose a major threat to life, a portacaval shunt is an effective means of reducing the cholesterol level. The benefits to the patient outweight the risks of operation. In one patient, an anxiety reaction developed which her psychiatrist related to a stressful situation. There were no clinical signs of encephalopathy, no response to protein restriction and a minimal elevation of the serum ammonia level, 86 versus 70 micrograms per cent as the upper limit of normal.