1 Ten consecutive patients with hypertriglyceridaemia who adhered to a low carbohydrate diet without complete control of serum triglycerides were started on chenodeoxycholic acid 750 mg daily and followed monthly for 6 months. Nine of these patients were then followed for a further month on placebo capsules and thereafter monthly for a further 6 months on clofibrate 2 g daily. 2 The mean serum triglyceride level fell by 36% after dietary treatment alone (P less than 0.05) and by 47% from initial values on diet plus chenodeoxycholic acid (P less than 0.01). In the nine patients who proceeded to clofibrate therapy there was a rise in triglyceride levels on placebo capsules to the level achieved by diet alone, and a further fall on diet plus clofibrate of 47% of initial values (P less than 0.05). 3 Chenodeoxycholic acid therapy is effective in the management of hypertriglyceridaemia not completely cured by dietary measures, and may be as efficacious as clofibrate.