Clinical investigations of acute confusion have largely been initiated in the acute care setting, where no uniform patient assessment exists. No reliable estimates of the prevalence of acute confusion in long-term care (LTC) residents have been reported. Delirium indicators are present in the nursing home Minimum Data Set (MDS), suggesting that MDS assessments could be used to facilitate studies of acute confusion in LTC. Methods to study acute confusion in LTC are discussed, with an emphasis on the advantages and disadvantages of using secondary analysis of MDS assessments as one research strategy.