This descriptive study was conducted to determine the validity and reliability in Turkey of the PediatricQuality of Life Inventory Cancer Module (PedsQL 3.0) for children aged 8-12 in the hematology-oncologypolyclinics of two university hospitals in Istanbul during the period 2006-2007. The data collection instrumentswere the Pediatric Quality of Life Inventory (PedsQL 4.0), the Pediatric Quality of Life Inventory Cancer Module(PedsQL 3.0) and a socio-demographic questionnaire, applied for 146 children diagnosed with cancer and 146parents. Cronbach’s alpha coefficients for the PedsQL 3.0 were found to be 0.602-0.982 for sub-groups withthe children’s form, 0.644-0.966 with the parents’ form. The scale was found to give a significantly high level ofreliability (0.60≤ ± α <0.80). Significant and directly proportional correlations were demonstrated between theforms for children and parents. It was concluded that the PedsQL 3.0 cancer module is a valid and reliable toolfor assessing the quality of life of Turkish children, aged 8-12, diagnosed with cancer.