Background: Undernutrition contributes to nearly 50% of all child deaths in the world, yet there is conflicting evidence regarding the association between nutritional status and postoperative complications. The aim was to describe the preoperative nutritional status among pediatric surgery patients in Zimbabwe, and to assess if nutritional status was a risk factor for adverse postoperative outcome of mortality, surgical site infection, reoperation, readmission, and longer length of stay. Methods: This prospective observational cohort study included 136 children undergoing surgery at a tertiary pediatric hospital in Zimbabwe. Nutritional status was standardized using Z-scores for BMI, length, weight, and middle upper arm circumference. Primary outcomes after 30 days included mortality, surgical site infection, reoperation, and readmission. Secondary outcome was length of stay. Univariate and multivariable analyses with logistic regression were performed. Results: Of the 136 patients, 31% were undernourished. Postoperative adverse outcome occurred in 20%; the mortality rate was 6%, the surgical site infection rate was 17%, the reoperation rate was 3.5%, and readmission rate was 2.5%. Nutritional status, higher ASA classification, major surgical procedures, and lower preoperative hemoglobin levels were associated with adverse outcome. Univariate logistic regression identified a seven-fold increased risk of postoperative complications among undernourished children (OR 7.3 [2.3-22.8], p = 0.001), and there was a fourto six-fold increased adjusted risk after adjustment for ASA, major surgery, and preoperative hemoglobin. Conclusion: A third of all pediatric surgery patients were undernourished, and undernourished children had a considerably higher risk of adverse outcome. With a positive correlation identified between undernourishment and increased postoperative complications, future aims would include assessing if preoperative nutritional treatment could be especially beneficial for undernourished children. (C) 2020 Elsevier Inc. All rights reserved.