Applied kinesiology is a technique used to assess nutritional status on the basis of the response of muscles to mechanical stress. In this study, 11 subjects were evaluated independently by three experienced applied kinesiologists for four nutrients (thiamin, zinc, vitamin A, and ascorbic acid). The results obtained by those applied kinesiologists were compared with (a) one another, (b) standard laboratory tests for nutrient status, and (c) computerized isometric muscle testing. Statistical analysis yielded no significant interjudge reliability, no significant correlation between the testers and standard biochemical tests for nutrient status, and no significant correlation between mechanical and manual determinations of relative muscle strength. In addition, the subjects were exposed in a double-blind fashion to supplements of thiamin, zinc, vitamin A, and ascorbic acid and two placebos (pectin and sucrose) and then re-tested. According to applied kinesiology theory, "weak" (indicating deficiency) muscles are strengthened when the subject is exposed to an appropriate nutritional supplement. Statistical analysis revealed no significant differences in the response to placebo, nutrients previously determined (by muscle testing) to be deficient, and nutrients previously determined (by muscle testing) to be adequate. Even though the number of subjects (11) and nutrients (4) tested was limited, the results of this study indicated that the use of applied kinesiology to evaluate nutrient status is no more useful than random guessing.