Introduction: Oral or enteral nutrition is recommended for admitted children, short-term nutritional supplement parenteral nutrition ( PN) is helpful for children with some nutritional deficiencies. Children who are admitted to special hospitals can receive specially dispended PN individually, but not many other hospitals. Instead, three-in-one (3-in-1) PN commercial products are widely used, but children lack efficacy and safety data. We aimed this study to evaluate the short-term efficacy and safety of 3-in-1 PN product in young children. Patients and Methods: We recruited inpatient children who were expecting nutritional deficits between 2 and 11 years of age. The 3-in-1 PN commercial product (560ml, 400kcal, MG TNA®-peri Inj.) was supplied for 5 days for 24 hours. We have collected age, sex, diagnosis, underlying disease and medication history. We calculated estimated energy requirement in each child. We monitored daily caloric intake, body weight and adverse events during PN supplementation, and confirmed laboratory data on day 0, 2 and 6. Results: Twenty-nine patients (14 males and 15 females) were recruited. The mean age was 7.5±2.7 years (range: 2.8-11.9 years) and the mean body weight was 23.3 kg. Twenty-four patients completed the 5-day PN supplement, while six patients stopped studying for early discharge or withdrawal of consent. The average daily oral caloric intake during study periods was 822 kcal and only fulfilled 54.1% of estimated energy requirement. Prealbumin increased significantly of 14.5±4.9, 16.3±5.3 and 21.6±4.9 mg/dL on day 0, 2, and 6 (p0.001). Transferrin also increased significantly of 215.9±29.9, 220.2±30.2 and 235.7±29.7 mg/dL on day 0, 2, and 6 (p=0.004). The overall average caloric intake in each child was 80.4% of estimated daily requirement. All other clinical and laboratory data showed no significant issue. Four patients experienced adverse events, but no adverse events associated with PN supplementation. Conclusions: Short-term use of 3-in-1 PN supplementation can effectively compensate deficit caloric intake during acute illness in children. Short-term use of 3-in-1 PN increase prealbumin and transferrin without any clinical and laboratory safety concerns.