Five ponies and one donkey with hyperlipaemia that occurred secondarily to a variety of primary clinical conditions were treated with lipid-free partial parenteral nutrition comprising equal volumes of 50 per cent glucose and 15 per cent amino acids. The infusion supplied energy and protein at rates of 2·6 kJ/kg per hour and 34·3 mg/kg per hour, respectively. In all six cases there was a prompt and sustained decrease in serum concentrations of triglyceride. In four of the six cases a good response to treatment of the primary condition was also seen and the subjects were discharged successfully. In the remaining two cases, poor clinical response of the primary condition resulted in euthanasia, although hyperlipaemia was nevertheless resolved. The main complication of parenteral nutrition was hyperglycaemia.