Influenza infection adds to the morbidity and mortality in cancer patients. This paper reviews studies on the ability of adult cancer patients to develop a protective immunological response to influenza vaccination. The studies showed that patients undergoing chemotherapy were able to develop an immunological response and seroprotection. The ideal administration time in the course of a chemotherapy treatment was unclear, but the longest time from chemotherapy was preferred. Repeated vaccination may be beneficial. Influenza vaccination is safe, inexpensive and easily available.