BACKGROUND Over the past 10 years, infection has remained as the main cause of illness and mortality among children with Acute Lymphoblastic Leukemia on chemotherapy. The high incidence of Hospital-Acquired Pneumonia in children with Acute Lymphoblastic Leukemia on chemotherapy with risk factors should be intervened earlier. METHODS An observational case control study of children with Acute Lymphoblastic Leukemia on chemotherapy. Patient with Hospital-Acquired Pneumonia considered as case and patient without Hospital-Acquired Pneumonia as control to analyze risk factors that affect the incidence of Hospital-Acquired Pneumonia in children with Acute Lymphoblastic Leukemia on chemotherapy from 2016 to 2018 was performed in the pediatric ward Dr. Soetomo General Academic Hospital with a total sampling technique. Nine risk factors were analyzed: age, gender, nutritional status, length of stay, risk stratification, chemotherapy phase, anemia, neutropenia, and thrombocytopenia. Bivariate and multivariate analysis using chi-square, continuity correction, and logistic regression was used for statistical analysis. RESULTS 120 children enrolled the study. Analyzed of risk factors showed risk stratification (p = 0.009), chemotherapy phase (p < 0.001), and neutropenia (p < 0.001) was proven to significantly affect the incidence of Hospital-Acquired Pneumonia in children with Acute Lymphoblastic Leukemia on chemotherapy. Age, gender, nutritional status, length of stay, anemia, and thrombocytopenia were not proven to be a risk factor that affects the incidence of Hospital-Acquired Pneumonia in children with Acute Lymphoblastic Leukemia on chemotherapy. CONCLUSIONS The incidence of Hospital-Acquired Pneumonia in children with Acute Lymphoblastic Leukemia on chemotherapy is significantly affected by the risk stratification, chemotherapy phase, and neutropenia.