Specialised system for computer assisted prediction of antiulcer activity of chemical compounds on the basis of their structural formulae is described. Predicted activity spectrum includes antiulcer activity, antisecretory and gastroprotective effects; H2- and M1-receptors blockade, H+, K(+)-ATPase inhibition as the mechanisms of antisecretory effect. It is shown that the average prediction accuracy is 83% in leave-one-out cross validation and 82% for the independent test set. Prediction made for about 300 new chemical compounds provides the selection of 20 potential antiulcer agents, 9 of them were synthesised and tested, 5 compounds have potent antiulcer activity. The discovered antiulcer agents are classified as New Chemical Entry because antiulcer and close effects have not been earlier for any compound of this chemical series.