Experiments were conducted to determine the palatability and digestibility of corn oil by ponies. A 15-day palatability trial established 20% as the maximum level of corn oil readily consumed by the ponies. Three digestion trials were conducted with eight mature gelding ponies weighing about 225 kg (incomplete Latin squares). A 7-day preliminary period preceded each 7-day collection period. Canvass collection bags and harnesses were used to collect total fecal excreta. In each trial, two ponies were fed each of four rations. The basal ration was composed of chopped alfalfa hay, cracked corn and crimped oats. In the experimental rations, corn oil was substituted for 5, 10 and 20% of the basal ration. At the end of each trial blood samples were taken. Addition of oil to the ration did not affect the apparent digestibility of crude protein. Apparent digestibility of fatty acids increased linearly with the level of corn oil. Values were 43, 62, 70 and 85% for rations containing 0, 5, 10 and 20% corn oil, respectively. Apparent digestibility of fatty acids in the corn oil, calculated by difference increased with level of corn oil. The value was 94% for the oil when substituted for 20% of the basal ration. Blood hemoglobin and hematocrit were normal and were not affected by feeding corn oil. Serum cholesterol increased from the addition of corn oil (122, 144, 148, 155 mg/100 ml for rations containing 0, 5, 10 and 20% oil, respectively). Serum triglyceride levels were not affected by ration fed. Serum calcium and magnesium levels remained in the normal range, and were not consistently affected by the corn oil level in the ration.