Mothers of 294 children aged 3–9 years were interviewed about their child's previous history of vaccinations and infections. The study group comprised healthy children selected at GP surgeries (n= 136) and those hospitalized for both minor and serious conditions (n=168). The results evaluate the entire study group for the pattern of reporting vaccinations and infectious episodes under three years of age, comparing two different data sources - mothers' reports and GP records. Maternal recall accuracy is formally tested (Kappa statistic) for agreement with GP records. For vaccination history the results indicate that mothers and GPs are inadequate data sources, and suggest use of computerized health district records to improve data accuracy. Major differences on infectious history were evident for two types of questions - closed for specific infections and open-ended for ‘other infections’. Specific infections (e.g. measles) were systematically over-reported by mothers compared with GP records, but mothers failed to ‘time’ the event. Concordance for ‘other infections’ was also poor, but, by contrast, GPs systematically over-recorded this range of infections, indicating substantial inaccuracy in mothers' recall. The authors suggest that GP records should be the preferred source of data for these ‘other’ infectious episodes, especially under one year of age. Improved questionnaire design would elicit more accurate maternal reports on specified infections for which a GP may well not be consulted and corroboration would be impossible.