A necessary prerequisite for reducing infant morbidity associated with passive smoking is effective measurement of this health risk factor. The purpose of this review was to evaluate questionnaires currently used in research to measure infant environmental tobacco smoke (ETS) exposure. Systematic searches were conducted using MEDLINE and CINAHL databases to identify current studies of infant ETS exposure. Sixty research reports published between 1996 and 2002 met the selection criteria. All of these investigations used brief investigator-developed, parental self-reports; no two studies used the same questionnaire. Reliability testing for questionnaires was lacking. Preliminary support for concurrent and construct validity is presented. Nursing studies are needed that lead to the development of ETS exposure questionnaires with established reliability and validity that measure both risk and protective mechanisms that occur in the infant environment.