Investigators have suggested that attitudes of faculty members toward diagnostic testing may encourage inappropriate laboratory use. In the present paper, the authors present a method for determining faculty attitudes on laboratory tests and the results of an analysis of such attitudes at one institution. The attitudes were determined from case simulations prepared by the faculty for senior medical student examinations. At the time the examination was being constructed, the faculty members weighted each laboratory test option following the case presentation for its appropriateness as positive, zero, or negative. The investigators subsequently categorized all of the laboratory tests according to their purpose and appropriateness with respect to the likelihood of diagnostic possibilities generated by the case. The results of the analysis showed that screening tests and tests to investigate unlikely diagnoses usually received weights close to zero and rarely received negative weights. This apparent indifference to tests with limited usefulness that generate some costs may be perceived by students as permission for their continued use. © 1985 Association of American Medical Colleges.