Cancer is one of the most devastating diseases in children. Diagnosis and treatment ofrncancer in children has effects that can limit their functional roles in daily life which willrncause disruption in their quality of life. However, there is a limited study that assess thernquality of life of children in Ethiopia. This study aimed to assess health related quality ofrnlife and determinant factors among children and adolescent cancer patients at TikurrnAnbessa Specialized Hospital cancer center, Addis Ababa, Ethiopia. The study wasrnconducted from May-June 26, 2020 using cross sectional study design. Sixty-nine childrenrnand adolescents with their parents/proxy had participated. Data was collected usingrnPedsQL Inventory tool of the generic core scale, cancer module and multidimensionalrnfatigue scale from both child and parents/proxy. Data was analyzed using SPSS 24 andrnANOVA and t test were used to evaluate mean difference among variables. Multiple linearrnregression was used to identify predictors of HRQoL. Children and adolescents aged fromrn8-18 participated in this study and 40 were male while females were 29. This study foundrngeneric quality of life mean score of 69.0 and 66.8 also cancer quality of life mean scorernof 74.5 and 72.48 based on child self and parent/proxy reports respectively. Lower scoresrnwere observed in physical function, emotional function, nausea and communication.rnClinical characteristics of patients had shown significant relation with generic and cancerrnscores. Fatigue, treatment duration, cancer type and treatment status predicted HRQoL ofrnchildren and adolescent cancer patients. Symptom management and Psychological supportrnin the initial phases of the treatment should get attention by clintians.