Abstract： Objective To investigate the effects of hyperbaric oxygen (HBO) on intracephalic angiogenesis in rats with intracerebral hemorrhage (ICH) and the mechanism involved.Methods The healthy SD rats were randomly divided into the sham surgery group (group A),the intracerebral hemorrhage group (group B) and the HBO group (group C).Observations were made on changes in rat behavior of each group.Expression levels of proliferating cell nuclear antigen (PCNA),yon Willebrand 's factor (vWF),hypoxia inducible factor-1 (HIF-1 α) and vascular endothelial growth factor (VEGF) were detected in the brain of rats of all the groups.Results Significant differences could be noted in behavior scores of the HBO group at d 14,d 21 and d 28,as compared with those of group B,with obvious statistical significance (P ＜ 0.01).The expression of HIF1-α in the brain tissue around the hematoma was higher than that of group B,and statistical significance could be seen in the expression levels at d 14,d 21 and d 28,when comparisons were made between the 2 groups (P ＜ 0.01).The expression of PCNA in the brain tissue around the hematoma for the animals of the HBO group was higher than that of group B,and statistical significance could be seen in the expression levels at d 14,d 21 and d 28,when comparisons were made between the 2 groups(P ＜ 0.05).The expression of VEGF for the HBO group was higher than that of group B,and statistical significance could be seen in the expression levels at d 14,d 21 and d 28,when comparisons were made between the 2 groups(P ＜0.01).The expression of vWF for the HBO group was also higher than that of group B,and statistical significance could also be seen in the expression levels at d 14,d 21 and d 28 (P ＜ 0.01).Conclusions HBO could accelerate angiogenesis of the damaged tissue induced by cerebral hemorrhage,promote absorption of hematoma,enable recovery of behavioral capacity and enhance rapid rehabilitation of the body,through expressions of such related factors as HIF-1 a,VEGF,PCNA and vWF proteins.