The result of the treatment of 70 ambulatory schizophrenic patients with high doses ofnicotinic acid or nicotinamide and evaluation and positive scores on the Hoffer-Osmond Diagnostic Test (HOD) is reported in this paper. Forty of these patients had been in hospital one or more times. One patient had amassed a. total of 300 ECTs, one had been subjected to lobotomy, six were sufficiently disturbed to require hospitalization so that treatment could be started. Three patients resident in hospital at the start of treatment are still in residence but were dropped from this study because the administration of the medication was haphazardly supervised so that the patients could either take the tablets or discard them at will. All the patients have been ill for many years and all had been treated either by psychotherapy, hospitalization, ECT and chemotherapy or any combination of these. At present they have been in treatment with niacin and ascorbic acid for 3-9 months. In many of the cases an anti-depressant was added when indicated. The results are shown in Table 1 (p. 24). These results on a particularly difficult group of patients are very encouraging and corroborate the findings of Hoffer et al. (1957).