Abstract： Objective Observe the expression of Interleukin-1β (IL-1β) in perihematomal regions (PHT) after experimental hemorrhagic stroke in rat. Methods Hemorrhagic stroke rat model was made by injecting collagenase Ⅶstereotaxically. Reverse transcription-polymerase chain reaction was used to measure expression of IL-1βmRNA in PHT. The level of IL-1β potion in perihematomal region and in blood was measured dynamically by immunohistochemically (SP methods) and enzyme-linked immunosorbent assay. Results IL-1βmRNA and IL-1βprotein significantly increased in early phase (4 hours) and reached a peak in 24 hour and decreased at 3 days in PHT after experimental hemorrhagic stroke, same as in brain edema after experimental hemorrhagic stroke.Conclusion IL-1β may play a role in brain edema and the following damage. Control of anti-IL-1β molecules might have brain edema and secondary damage in PHT after experimental hemorrhagic stroke.