When response errors are studied by means of record checks, the possibility exists that matching errors are made in relating responses to the corresponding record data. Two simple models are developed for matching errors, and the implications of such matching errors on various measures of response errors are studied. The models are applied to the data from a record check study, and it is found that relatively small imperfections in the matching process can lead to substantial bias in estimating the relationship between response errors and “true” values.