Background: Pediatric cancer patients have increased survival rates with intensive and effective treatment methods which causing some chronic health problems and lower quality of life in long term follow up. In our study, patients in their active treatment period compared to patients who have completed their treatment in recent 5 years and more than 5 years groups, besides compared with their own siblings and healthy control group,evaluated in terms of quality of life ( QOL). Methods: This study has been daone in the Department of Pediatric Hematology-Oncology, Ankara University School of Medicine. A total of 191 children were included in the study, including 36 sibling, 76 children with leukemia (n:31) and lymphoma (n:45) besides 79 healthy children. The Turkish translation of the PedsQL questionnaire was used to evaluate the patients' quality of life. IBM SPSS-25 package program was used for statistical analysis. Results: When the sociodemographic characteristics of the patient, sibling and control group were examined; we determined that the patients, siblings and control groups were similar in age, age and gender. However, we found that the education level for the patient group was statisticaly signicantly lower then the siblings and the control group. In addition, physical and mental functionning and friendship capasity scores were lower in patient group than the other two groups. According to timing of the treatment; patients and parents quality of life scores were significantly lower than the patients that finished their treatment in recent 5 years or more than 5 years. QOL scores were higest in survivors and parents group that were in more than 5 years after completed the treatment. The risk of lower QOL in patients under treatment was 7.48 times higher than the children who had ≥5 years of treatment (OR = 7,48; p < 0,05), and 2.64 times higher than those who were treated < 5 years (OR = 2,64; p > 0,05). In this study, there were no independent variables that had an impact on QOL of the sibling group. Conclusions: The QOLof patients diagnosed with leukemia and lymphoma is significantly lower than siblings and healthy group. No statistically significant difference was found between the sibling group and the healthy control group. After the end of active treatment, the QOL of the patients was reflecting important increase by the time .