Oral mucositis can be caused by chemotherapy and can affect a patient’s quality of life. Nowadays, to prevent chemotherapy-induced oral mucositis (CIOM) is a crucial point in palliative care centers. This trial aimed to assess the effectiveness of aloe-vera in that concept. The trial was accomplished at Hematology Department of Hospital of Children of Damascus University, Syria. Acute lymphoblastic leukemia (ALL) children were the population from which 26 children were enrolled in the study. They were aged between 3 and 6 years old and were randomly referred according to the intervention into two groups, Aloe-vera (AV) and sodium bicarbonate 5% (13 each). Spongeous sticks were used to help in applying the material on tongue, labial and buccal mucosa, lips, floor of the mouth, and hard palate. Two blinded external examiners evaluated oral mucosa weekly for up to 2 months using the World Health Organization grading scale. Mann-Whitney U test was used to analyze data. According to the observed findings, CIOM degrees were less severe in the aloe-vera group than in the sodium bicarbonate group. Statistically significant difference of occurrence of different CIOM degrees between groups was recorded in the 2nd, 3rd, 4th, and 7th weeks of follow-up period. Moreover, Mann-Whitney U test indicated that patients in the sodium bicarbonate group began CIOM sooner than those in the aloe-vera group with a statistically significant difference ( = .001). These findings show that topical application of aloe-vera solution is effective in the prevention of CIOM in ALL children.