A duplicate diet study has been carried out on a group of Harwell employees in order to investigate the food types in which radiocaesium from Chernobyl was most likely to be found, and also the intake of radiocaesium in food with relation to observed whole‐body levels. The duplicate diet study indicated that the highest levels of radiocaesium were in milk and meat or fruit and vegetables. Radiocaesium concentrations in food of all types are small compared to the most restrictive generalized derived limit. Daily intakes of radiocaesium measured by the diet study, of the order of 2–3 Bq day−1, generally agreed with values calculated from whole‐body measurements. Committed doses from radiocaesium have been estimated from dietary intakes to be in the range 3–29 μSv year−1, while whole‐body measurements indicate a range of 6–18 μSv year−1; these doses are small compared to other sources of internal irradiation and to recommended limits.