The authors sum up the experience gained in tactivin therapy of patients with recurrent aphthous stomatitis and analyze the effects of this drug on the patients' cellular and humoral immunity. Thirty patients with various forms of the condition were subcutaneously injected tactivin in a dose of 40 micrograms for 10 days. Biochemical parameters were virtually unchanged after therapy, whereas the immunity parameters evidenced essential shifts in humoral and cellular immunity. Clinical and laboratory data indicate a sufficiently high immunocorrective effect of tactivin in therapy of patients with recurrent aphthous stomatitis.