Background: Children and adolescents with cancer are at risk of a poor health-related quality of life. Exercise interventions to enhance movement may be a valid strategy for managing some symptoms, including fatigue. Methods: Forty-four consecutive patients (20 females; aged 5-21 years old, median 15.5 years), without any contraindications significantly limiting their movements were invited to join an in-hospital 6-week supervised exercise program, and asked afterwards to complete the PedsQL-4.0 quality of life Generic Core Scales and the PedsQL Multidimensional Fatigue Scale. The program consisted of personalized workout sessions of aerobic, resistance and flexibility exercises. The results obtained on the scales were compared between patients who engaged in the exercise program (GYM group, n=21) and those who did not (No-GYM, n=23), with the aim of examining the different dimensions of health-related quality of life (physical, emotional, cognitive, social) and fatigue (general, sleep/rest, cognitive) comparing the two groups. Results: For 43 of 44 patients, being diagnosed with cancer initially prompted a drop-out from previous physical exercise or sports routines despite no contraindications to their continuation. After 6 weeks, the scores for patients in the GYM group showed a statistically significant better perceived emotional functioning, and a possible indication of improved social functioning compared with the No-GYM group. Conclusion: These findings suggest that to exercise improves the satisfaction of children and adolescents with cancer with their physical, mental and social functioning. It is worth further investigating the value of systematically including exercise workouts in their routine cancer practices.