The incidence of gastric ulcers remains at a fairly high level: it is diagnosed annually in 7‐14% of the adult population. Despite the decrease in morbidity and the development of diagnostic methods as well as effective treatment, the number of complications such as bleeding and perforation is increasing. One of the significant pathological factors leading to the gastric injury is disturbances in blood flow through mucosal microvessels (providing oxygen and nutrients). In this regard, it becomes relevant to study drugs that affect the rheological properties of blood and microcirculation.This study aimed to investigate the effect of heparin on the formation and the healing of the experimentally induced gastric ulcers in rat. Adult male Sprague‐Dawley rats weighing 230‐250 g were used after 24 h preliminary fasting. Gastric ulcers were produced by luminal application of 60% acetic acid to an area clamped with a pair of forceps (kissing ulcer model developed by S. Okabe) in anesthetized rats. Day 4 after the application (Day 0) was chosen as the time point for the ulcer formation, and Day 7 was chosen as the time point for incomplete ulcer healing. Heparin was injected at a dose of 1000 U/kg (s.c., once a day). While studying the effect on the ulcer formation, heparin was injected daily from Day 0 to Day 3. While studying the effect on the ulcer healing, heparin was injected daily from Day 4 to Day 6. Control rats were injected with saline. The blood hemoglobin levels were evaluated before the acid application surgery and in the end of experiments.The heparin injection before the ulcer formation resulted in a decrease of the ulcer area. The average area of kissing ulcers in heparin‐treated group was significantly smaller than that in the control group (p <0.05). The ulcer healing was significantly accelerated in the heparin‐treated group in comparison to the control group (p < 0.05). Blood hemoglobin levels were decreased in both heparin‐treated and control groups without significant differences between the groups.The results suggest that heparin therapy has the potential to accelerate gastric ulcer healing and prevent their formation.