OBJECTIVE: To compare the safety and immunogenicity between a MF59-adjuvanted influenza subunit vaccine and a conventional non-adjuvanted influenza subunit vaccine. METHODS: A randomized, blind-designed controlled study was carried out, with 600 subjects (> or = 60 years of age) received MF59-adjuvanted influenza subunit vaccine (FLUAD, n = 400) or conventional non-adjuvanted influenza subunit vaccine (Agrippal, n = 200) respectively. The local and systemic reactions were observed on 0-7 days after vaccination. Haemagglutination inhibition (HI) titers of pre-and post-vaccination were detected by the HI assay. Seroconversion (4-fold increase) rate of subjects was calculated using baseline data when it was under naive level, and the protection rate when HI titer achieving the level of protection (> or = 1:40) after vaccination. Geometric mean titer (GMT) and its increasing folds were calculated. Differences between safety and immunogenicity were also calculated. RESULTS: The local and systemic reaction rates were similar between both groups, but the duration in injection site was frequent for Agrippal (P < 0.05), while mild pain and fever in injection site were frequent for FLUAD. On immunogenicity test, for those subjects whose baseline was under naive level while the seroconversion rate against A/H3N2 viral strain after vaccination--FLUAD was significantly higher than Agrippal (P < 0.001). Aside from A/H1N1 viral strain, the rate of protection on both groups were significantly higher than those from baseline data, but for A/H3N2 viral strain, FLUAD was significantly higher than Agrippal (P < 0.001). GMT was higher than baseline (P < 0.001) after both groups being vaccinated but FLUAD group was significantly higher than Agrippal group. CONCLUSION: FLUAD was well tolerated by Chinese elderly and its immunogenicity level induced by FLUAD was higher than that of Agrippal, showing that it would benefit the elderly with hypoimmunity.