Background: To normally grow and develop, children with congenital heart diseases (CHD) in the hypermetabolic state need 50% more energy than healthy ones. Objectives: This study aimed to investigate the prevalence of malnutrition and its association with other factors among the nonsyndromic acyanotic patients with CHD undergoing palliative or corrective surgery. Methods: A retrospective study of medical records of 812 children with acyanotic congenital heart disease undergoing palliative or corrective surgery was performed from March 2011 to March 2017. Collected data consisted of the age at the time of the surgery, gender, weight at the time of the surgery, height at the time of the surgery, birth weight, length of ICU stay, and 1-year mortality. The WAZ, WLZ, LAZ, and BMI Z-scores were calculated based onWorld Health Organization (WHO) standards. We classified the Z-scores into 4 groups, including normal (Z-scores >-1), mild (-2 to >-1), moderate (-3 to >-2), and severe (<-3) malnutrition groups. Results: Total amount of 812 patients, 375 (46. 2%) were female and 437 (53. 8%) male, participated in this study. The average age, weight, and height at the time of the surgery were 23. 52 + 29. 38 months, 9. 086 + 6. 71 kilograms, and 76. 93 + 23. 37 centimeters, respectively. Moreover, 68. 7% and 66. 4% of the patients suffered from mild to severe forms of malnutrition based on WAZ and WLZ, respectively (P value < 0. 0001, 0. 025). There was no significant difference between males and females in WAZ, WLZ, LAZ and, BMIZ (P value: 0. 154, 0. 265, 0. 965, and 0. 667, respectively). Generally, in acyanotic defects, we found that more severe malnutrition causes an increment in length of ICU stay (P value = 0. 001) and lesser birth weight has a significant relationship with the severity of growth failure in infancy or childhood (P value < 0. 0001). Conclusions: In our study, the high prevalence of the malnutrition and related complications during and after surgical repair shows the importance of nutritional support and interventions in patients with CHD.