The present study was examined the therapeutic effect of medium-chain triacylglycerol (MCT) in protein-energy malnutrition (PEM). Wistar rats were fed low protein diet containing 70 g/kg of long-chain triacylglycerol (LCT) or MCT for 31 days. The serum albumin concentration in rats fed MCT diet (2.88 ± 0.04 g/dl) were significantly higher compared with those fed LCT diet (2.72 ± 0.04 g/dl) at day 31. Nitrogen balance was higher in rats fed MCT diet (54.1 ± 2.3 mg/day) compared with those fed LCT diet (45.4 ± 2.4 mg/day) during d 10–12. These results suggest that MCT effectively elevates serum albumin concentration and improves nitrogen balance in malnourished rats.