The present study was started to investigate the problem of whether or not vitamin C administration may help control autoimmune disease and allergy by stimulating the glucocorticoid mechanism of a patient with an immune disorder. Our study was expected to give an answer to the long-lasting enigma of endocrinology--why is the adrenal cortex so rich in the vitamin C content? Our investigation represents the complex of experimental and clinical study. A healthy male volunteer served as the test subject in the experimental study, and we investigated the effect of vitamin C injection or infusion treatments on the eosinophil count and 5 plasma steroids in plasma on the one hand, and also tested the effect of vitamin C treatments on diuresis and 17-hydroxycorticoids (17-OHCS) excretion on the other hand. In the clinical study, the effect of the vitamin C infusion treatment on immune disorders was assessed in 4 patients with autoimmune disease. Results obtained are as follows: 1) the vitamin C injection or infusion treatments induced an increase of plasma glucocorticoid activity with a delay of about 2 hours, as assessed in terms of the eosinophil count and plasma cortisol concentration. 2) Within 2 hours after vitamin C challenge, however, a remarkable decline of plasma cortisol was found to proceed without any corresponding change of the eosinophil count, a finding to suggest the presence of some cortisol absorber, of which the function was triggered by vitamin C. 3) The same vitamin C treatments also accelerated diuresis and 17-OHCS excretion.(ABSTRACT TRUNCATED AT 250 WORDS)