Thirty-seven previously diagnosed reactive hypoglycemic patients (HP) were evaluatedand classified according to blood glucose nadir and plasma cortisol response to the nadir. We found eight definite, ten probable, and thirteen possible HP. Six patients were vaguely symptomatic without chemical evidence of hypoglycemia. Underlying etiology for the HP included nine diabetics, seven alimentary, thirteen idiopathic, one hypothyroid, and one with liver disease. The Minnesota Multiphasic Personality Inventory (MMPI) was given to all the patients and to twenty-one patients with various endocrine disorders without hypoglycemic symptoms. HP had mean scores two standard deviations above normal on hypochondriasis and hysteria scales with all other scales within normal limits. Definite, probable, and possible HP did not differ significantly from each other. HP differed significantly from mixed endocrine patients on the Hs and Hy scales (p < .001) and from vaguely symptomatic patients on the Hy scale (p < .05). The latter groups were normal on all scales. HP of varying etiology (diabetic, alimentary, or idiopathic) show the same MMPI pattern. Thispattern differs from that shown in previous MMPI studies of diabetic patients and patients with gastric surgery without hypoglycemia. Thus, a relationship between hypoglycemia, of whatever origin, and this specific personality pattern is suggested.