The objective of this study was to evaluate the validity of information reported by the elderly on 23-valent pneumococcal polysaccharide vaccine (23vPPV) vaccination status. A cross-sectional, observational study was carried out in patients aged >or=65 years admitted to five Spanish hospitals. Data on 23vPPV vaccination history were obtained through interview of the patient or close relative and review of written medical information. The validity of the patient self-report was compared to the written medical information by calculation of the sensitivity, specificity, concordance, positive predictive value (PPV) and negative predictive value (NPV). A total of 2484 patients were initially included of whom 1814 patients (73%) responded about their vaccination status. The global sensitivity of the patient self-report was 0.74 and the specificity 0.95. The PPV was 0.92, the NPV 0.84 and the concordance 87. Vaccination cards and centralized vaccination registries in primary health care centres and hospitals should be potentiated in order to ensure that neither more nor less vaccinations are administered than are necessary.