The low molecular fraction (below 5 kDa) was extracted from cord blood by ultrafiltration. It has been shown that the cord blood fraction possesses antiulcer activity on the model subchronic stomach ulcer. The cord blood fraction injections caused a significant reduction in the area of ulcer lesions and promoted recovery of microcirculation, thickness, and structure of gland layer, which was accompanied by a decrease in leucocytes infiltration and an increase in glycosaminoglycans synthesis. That resulted in a faster recovery of mucus membrane of stomach as compared with Actovegin. Application of the cord blood fraction in animals with stomach ulcer normalized the alkaline phosphatase activity and thiobarbituric acid-active product content. Gelpenetrating chromatography showed that the patterns of the low molecular substances from cord blood and Actovegin differed both qualitatively and quantitatively.