Objectives: The aim of the current study was to investigate the illness perception among adolescent cancer patients and to research its possible relationship with depression and anxiety. It was also aimed to make some proposals that would contribute to the content of the interview with the newly cancer-diagnosed adolescents. Materials and Methods: Forty adolescents (55% female) between the ages of 14 and 18 years, who were newly diagnosed with cancer [40% lymphomas, 25% sarcomas, 15% central nervous system (CNS) tumors, and 20% other cancer] were enrolled to the study. Illness perception, Beck depression and Beck anxiety scales were used to collect data. Gender and type of cancer were examined as independent variables. Results: It was found that the most common symptoms that were reported by newly diagnosed adolescents were pain, fatigue and power loss. According to cancer type groups, CNS tumor group significantly did not believe that they had personal control upon their illness. Depression scores of lymphoma and sarcoma groups were significantly higher than those of other tumor groups. Conclusion: The interview with the newly diagnosed adolescents should contain their illness perception characteristics. If some negative illness perceptions are detected, they should be replaced mentally with more accurate/positive ones. Adolescent should be said that everything would be done to reduce the symptoms such as pain. And emotional status of adolescents should be checked throughout the treatment.