A study is presented of the effect of copper vapors laser therapy on the content of biogenic amines--serotonin and histamine and the state of adenylcyclase (AC) system (content of cAMP, cGMP and AC activity) at the edge of the gastric ulcer. Direct effect of laser radiation (single dose 10--15 J.) produced a significant increase of serotonin, histamine, cAMP, AC activity and an insignificant increase of cGMP. Healing of the ulcerative defect after 5--6 laser therapy sessions was followed by a reduction of the content of serotonin, increase of histamine, cAMP and AC activity. The authors discuss the biostimulating effect of laser radiation by influencing the inflammatory-proliferative processes in the epitheliocytes in prolonged nonhealing gastric ulcers.