Influenza has a significant clinical impact on pediatric cancer patients because it causes frequent febrile episodes and respiratory tract infections, possibly severe complications, delays in chemotherapy administration and even death, all of which supports the importance of prevention and the widespread use of influenza vaccination. Results from clinical studies show that influenza vaccination can be considered safe in children undergoing chemotherapy and, although weaker than in healthy children, the immune response seems to be sufficient in patients with leukemia or solid tumors even if it is less in children receiving chemotherapy than in those who are not. However, there is an urgent need for universally accepted guidelines concerning the type of vaccine that leads to the best immunological results, the number of administrations, and their timing in relation to the severity of immunosuppression and chemotherapy schedules. Such recommendations, together with a clear demonstration of vaccine efficacy, are also needed to increase influenza vaccination coverage in this high-risk category of patients.