The diagnosis of cancer influences the lives of children in many ways. Instead of maintaining daily activities, children often visit hospitals or stay there for an uncertain period. Due to the disease and treatment, children experience suffering and pain, their school and play activities are interrupted and they become separated from social and familiar environments. This may cause several problems in their development and quality of life (QOL). QOL is the state of well-being in terms of physical, psychological and social aspects. According to surveys that investigate the negative effects of cancer on children’s QOL, “the loss of normalcy” and inability to play, do sports, spend time with family and friends are considered by children to be worse than the physical symptoms and side effects of the treatment. Children with cancer need play during hospitalization in order to pursue their development and to feel normal. A case study was conducted in Dokuz Eylül University Nevvar and Salih İşgören Children’s Hospital in order to understand the needs of children with cancer, provide a design suggestion for their play area, and especially investigate the effects of the participatory design process on QOL of children. A participatory design study was carried out in order to achieve more responsive results to participants’ needs by involving users in the design process. It was found out that the process contributes to the improvement of QOL of children by making them feel that their ideas matter as well as distracting them from negative thoughts regarding cancer. Keywords: Participatory design, generative techniques, design with/for children, quality of life (QOL), children with cancer, hospitalization, play area design