B ackground : Acute Lymphoblastic Leukemia (ALL) is a cancer that usuallyoccurs in children. LLA treatment with induction chemotherapy is a treatment thataims to eradicate over 99% of the initial load of leukemia cells and to restorenormal hematopoiesis and normal performance status. The side effects ofchemotherapy commonly occur in the oral cavity are oral mucositis. nowing thefrequency distribution of oral mucositis children with ALL who receivedinduction chemotherapy treatment. Objective : To determine the frequencydistribution of oral mucositis children with ALL who received inductionchemotherapy treatment. Methods : Research descriptive observational studywith cross cut design that was conducted in February 2017 in RSAB HarapanKita. This research was conducted by taking a sample data directly from thesubject under study with the inclusion criteria are patients with ALL boys andgirls aged 2-15 years who received induction chemotherapy. Taken form theclinical picture of the oral mucosa and patient medical records. The resultsobtained in this study were included in the criteria for inclusion are 9patients(20%) of 44 patients. Results: This study showed (1) of men 67% andwomen 33%, (2) the age of 2-9 years and 10-15 years 67% 33%, (3) the type ofALL, L-1 45%, L- 2 22%, L-3 33%, (4) the degree of mucositis oral scale of 1) to45%, a scale of 2) to 33%, scale 3) 22%, and the scale 4) 0%, (5) the location ofmucositis of the upper lip of 28%, lower lip 43%, the tongue 14%, floor of themouth 14%, (6) the length of chemotherapy <1 week 33%,> 1 week 11%,> 1month 56%, (7) the type of chemotherapy drugs alkylating agent 22%,antimetabolites 100%, antibiotics 44%, 56% vinca alkaloids. Conclusion : Oralmucositis with ALL who has induction chemotherapy mostly found less than 9years, boys are commonly affected rather than girls and generally located at thebottom of lips and tongue.