The reactogenicity and the humoral immune response to three influenza vaccines were evaluated in a randomised, double-blind trial at nursing homes in north-east Italy in winter 1998-1999. Of the 285 subjects, who completed the follow-up, 93 were administered virosomal vaccine, 99 received MF59-adjuvanted vaccine and 93 had split vaccine. Ten subjects (0.3%) reported local and/or systemic reactions in the first week after immunisation. After 4 weeks, protection rates (> or = 40) were near 100% for the H1N1 and B strain and 76.0% against H3N2. The MF59-adjuvanted vaccine group had higher geometric mean titres than the other two. However, the true clinical benefit of the new adjuvanted vaccine should be further substantiated by comparative protective studies. Our results suggest that immune response to influenza vaccination in institutionalised elderly is satisfactory.