The effects of Gerovital H3 (a specially stabilized form of procaine hydrochloride) on geriatric psychiatric patients were assessed in a double-blind study at Bronx State Hospital. The mean age of the subjects was 73 years and the average rating for the severity of organic symptoms was "moderate." During the first six weeks of study, the patients were each given a 5-ml injection of either Gerovital or placebo (saline) intramuscularly three times a week. This dosage was doubled to 10 ml per injection during the second six weeks. Nine Gerovital and 10 control subjects completed the first six weeks; and 6 Gerovital and 7 control subjects completed the entire 12-week study. Objective rating scales were used to evaluate patients on measures of interpersonal functioning, cognitive ability, psychiatric symptoms, and urine and blood chemical findings. All subjects were assessed before treatment and at six weeks and twelve weeks of the study. Side effects were recorded at two-week intervals. On most measures the variability between subjects was quite large, whereas differences between average scores for the two groups usually were small The few significant differences showed no systematic pattern and would be expected to occur by chance alone when so many statistical comparisons are made. The overall results of this double-blind study strongly indicated that, among these hospitalized geriatric patients with organic symptoms, Gerovital H3 had no ameliorative effect on either psychologic or physiologic functioning.