BACKGROUND: Acute lymphoblastic leukemia (ALL) is the most common malignancy in children. Febrile neutropenia is one of medical emergencies in ALL patients. One of the risk factors that associate with febrile neutropenia is malnutrition. Malnutrition reduce the body’s immunity that increase incidence of infection. AIM: aimed to prove malnutrition as risk factor in children with ALL who had febrile neutropenia METHOD: This is case-control study with samples a hundred children aged 1 month to 18 years old with ALL at Sanglah Hospital Denpasar between 2015 - 2021. Subjects were grouped into two, those with febrile neutropenia and without febrile neutropenia.  The relationship between malnutrition and febrile neutropenia was analyzed by using chi-square bivariate analysis test.   RESULTS: A hundred subjects were devided into two groups with 50 subjects each group. Bivariate analysis showed significant association between malnutrition and febrile neutropenia (OR 4.53; 95%CI 1.95 - 10.51; p-value <0.001). CONCLUSION: Malnutrition as risk factor for febrile neutropenia in children with ALL.