BACKGROUND: This study estimated the effects of ambient temperature on hospital admissions for hemorrhagic stroke during 2004-2009 in Jinan, China, and the effect modification of hypertension status. METHODS: The exposure-response relationship between temperature and hemorrhagic stroke was firstly examined, and then the association between daily mean temperature and hemorrhagic stroke was investigated using a generalized additive model. Stratified analyses were conducted to examine the potential effect modification of hypertension. RESULTS: A total of 1577 hemorrhagic stroke cases were observed between 2004 and 2009, among which, 1058 were hypertensive and 519 were non-hypertensive. We found an approximately linear relationship between ambient temperature and hemorrhagic stroke. Each 1 degrees C decrease in the current day's temperature was associated with 1.63% (95% CI: 0.33%, 2.95%) increase in daily hemorrhagic stroke. The stratified analyses observed that the association was significant among hypertensive hemorrhagic stroke, each 1 degrees C decrease in the current day's temperature was associated with 2.26% (95% CI: 0.57%, 3.98%) increase in daily hypertensive hemorrhagic stroke. While no significant effect was observed for non-hypertensive hemorrhagic stroke. CONCLUSIONS: Low temperature might be one risk factor for hemorrhagic stroke and hypertension may be one effect modifier of this association in Jinan, China.