An increasing number of patients have been presenting with multiple symptoms they attribute to low-level chemical exposures, ie, multiple chemical sensitivities (MCS). Although some studies have evaluated such patients, the selection criteria has not been rigorously defined. The present study is the first to use a relatively rigorous definition of MCS to select patients for study. Comprehensive evaluation of medical, psychiatric, neuropsychological, and immunological status of a series of MCS patients is presented. In contrast to previous studies, patients in this study did not have a history of psychiatric disorder. However, some patients were currently depressed. Neuropsychological assessment did not reveal any abnormalities with the exception of one test of verbal memory for which performance was consistently poor relative to the normative sample. No significant immunological abnormalities were noted.