Recent literature regarding barriers to care is reviewed, beginning with a discussion and comparison of the definitions of the barrier concept drawn from the health belief model and Andersen's model of health services utilization. The research literature which includes the barrier concept as a determinant in testing those models is reviewed, as well as research studies examining utilization behavior which do not have a well-articulated theoretical framework. Both nonempirical and empirical articles are reviewed to ascertain how the concept barriers to care is, or might be, operationalized. Although similar indicators are used from study to study, the review uncovers considerable confusion regarding the barrier variable both theoretically and empirically, which apparently results from lack of methodological rigor in defining and operationalizing the concept.