<i>Introduction:</i> Hospital-acquired malnutrition is one aspect of childhood malnutrition that healthcare professionals might not recognize. The prevalence of hospital-acquired malnutrition globally and in developing countries is still high varies between 6.1%-40.9%. Various factors contributed to the frequency of hospital-acquired malnutrition, including the nutritional status at the onset of the disease. <i>Material and Methods:</i> The prospective cohort study was conducted on the patients in Pediatric Ward at Sanglah General Hospital, Denpasar Bali period July 2020 and January 2021. We Include children aged one month to 18 years old. Samples were taken by consecutive sampling. Hospital-acquired malnutrition was marked by more than 2% loss of weight from the measurement during admission. Univariate analysis was performed using the chi-square test. Nutritional status presented as Prevalence Ratio (PR) and 95% Confidence Interval (95% CI). The result is considered as significant if p<0.05. <i>Results:</i> 208 subjects were included and analyzed in this study. Malnutrition incidence was 15.4%. The risk factors significantly associated with hospital-acquired malnutrition were an underlying disease, length of stay, admission nutritional status. Malnutrition, length of stay and underlying condition were the independent risk factors for hospital-acquired malnutrition with PR 7.528 (95% CI, 2.528-21.033; p=0.001), PR 9.061 (95% CI, 2.925-28.066; p=0.001) and PR 2.638 (95% CI, 1.0325-6.724; p=0.042). <i>Conclusion:</i> The incidence of hospital acquired malnutrition in Sanglah Hospital was 15.4%. Children with malnutrition, prolonged hospitalization length, and underlying disease are associated with hospital-acquired malnutrition.