The present study sets out to add to knowledge about the development over time of health-related quality of life (HRQL), anxiety and depression among survivors of adolescent cancer. The aim was to investigate if and how the HRQL, anxiety and depression of a group of adolescents with cancer differ from those of a reference group shortly after diagnosis, and subsequently at 6, 12 and 18 months after diagnosis. Adolescents diagnosed with cancer and a reference group randomised from the general population completed the Hospital Anxiety and Depression Scale (HADS) and the two subscales Mental Health and Vitality in the Short Form 36 (SF-36) in telephone interviews. The results indicate a steady increase in psychological well-being from the time of diagnosis, when the cancer patients' ratings were significantly worse than those of the general population, and onwards. The differences gradually disappeared and then were reversed, resulting in the cancer group reporting significantly better HRQL and lower levels of anxiety and depression than the reference group when 1.5 years had passed since diagnosis. The adolescents faced with cancer show signs of adaptation to trauma, which can be understood in relation to the theoretical framework of posttraumatic growth as well as response shift. Future research should continue to follow this development over time, to investigate if the positive effects of the cancer experience will wear off, or if it has facilitated a permanent positive outcome.