Influenza vaccine is considered to reduce influenza-related morbidity and mortality in patients with underlying chronic medical conditions. Because of fear of vaccine shortage during an influenza pandemic, several antigen sparing strategies have been investigated. The immunogenicity of intradermal influenza vaccination with one half the antigenic contents was compared to that of conventional intramuscular vaccination in patients with solid cancer, and adverse events were assessed after vaccination. There was no significant difference between the injection routes in the hemagglutinin inhibition (HI) response and increase in the titer of A/H1N1, A/H3N2, and B 4-6 weeks after the vaccination; seroconversion factors increased by more than 2.5-fold. Seroresponse rates were more than 40% and seroprotection rates were above 70% against all three influenza strains irrespective of the vaccination routes. No serious events were observed, and local skin reactions were more frequent in the intradermal injection recipients than in the intramuscular recipients (32.7% vs. 9.1%). This study shows that intradermal injection of one half the dose of a commercial influenza vaccine elicits immune responses comparable to those elicited by a full dose of intramuscular vaccine among cancer patients, and it can be tolerated without serious adverse reactions.