Background: Acute lymphoblastic leukemia (ALL) is the most common malignancy in children. The breakthrough in ALL treatment granted long event free survival reaching 90% of the patients. Even though the patients still show many adverse events during their treatment journey. These events were assignable to the disease or the side effects of the chemotherapeutic agents. Here, we sighted these adverse events in pediatric patients with ALL at South Egypt Cancer Institute, Assiut University, Egypt. Method: We performed a retrospective descriptive cohort study on 309 pediatric ALL patients with ages >1 to <18 years old at Pediatric Oncology Department, South Egypt Cancer Institute (SECI), Assiut University during the period from January, 2002 to December, 2017 and their follow up data were collected until December, 2019 . All adverse events that occurred during management of those patients and their outcome were analyzed according to the clinical and laboratory characteristics of the patients. Results: During study, 309 patients were eligible. Continuous complete remission was achieved in 159 (51.4%) of these patients. The adverse events emerged were evident in 66 (21.3%), 59 (19%) leukemic relapses, and 106 (34.3%) deaths. Adverse events due to chemotherapy were bone marrow suppression (grade II and III) in 45.3% and 25% respectively. Chest infection in 20% from which 75% bacterial and 25% fungal. Sepsis was diagnosed in 6.5% and gastrointestinal toxicity in 20%. Conclusion: The incidence of the adverse events during treatment was high in our institute.