A clinical response to and some mechanisms of therapeutic action of extremely high frequency (EHF) therapy were studied in 132 patients with exacerbation of duodenal ulcer vs routine pharmacological treatment. EHF-therapy was used alone and in combination with famotidin (antisecretory drug) and norfloxacine (antibacterial drug). EHF monotherapy proved highly effective in duodenal ulcer exacerbation. It normalizes secretory and motor functions of the stomach, suppresses initially high activity of free radical lipid oxidation, corrects abnormal vegetative and psychoemotional status of the patients, moderately potentiates the antihelicobacter effect of antibacterial drugs. These effects are produced due to specific action of EHF therapy: mobilisation of sanogenesis mechanisms, correction of mechanisms of adaptive regulation and self regulation at different levels. Additional administration of antisecretory and antibacterial drugs improved immediate but deteriorates long-term response to EHF-therapy.