Each patient with ulcer has his/her own 24-h biorhythm of acid production, features of food alkalization, duration of duodenogastric and gastroesophageal reflux. Pharmacological test conducted in prolonged 24-h pH-metry helps to select the most effective antisecretory drug, while analysis of 24-h biorhythm of acid production--optimal time for drug intake and number of its daily doses.