Phitopreparation tiol is offered (5% fatty solution of Tea Leaf lipid complex) as a medicine. To determine gastroprotective effect of tiol generally accepted models of acute gastric ulcer were used: bitadion, atopanove and reserprinove stomach damages. An experiment was conducted on half-matured white mice weighting 140-160 g., which fast 24 hours before the experiment (only water was freely given to them). Animals were killed by immediate decapitation under light ether narcosis. Their stomachs were dissected along greater curvature of stomach and number of injuries were counted. The injuries were subdivided into hemorrhage, erosion and ulcer. Paul's "ulcer index" was calculated for any kind of damage. Each group consisted of 5 mice. Distilled water was used as control and aekol - to collate the gastroprotective effect. Results of the experiment showed that gastroprotective effect of tiol is greater than that of aekol's.