Objective To investigate the changes of hematoma and perihematomal edema in spontaneous hypertensive rats (SHRs),as well as the correlation between blood pressures and perihematomal edemaMethods A total of 24 6-month-old male SHRs were included.They were randomly divided into intracerebral hemorrhage 1-,3-,5-,and 7-day groups (n =6 in each group).Blood pressure was determined by tail-cuff sphygmomanometry.Collagenase Ⅳ was injected into caudate nucleus in order to induce a model of intracerebral hemorrhage.Magnetic resonance T2 weighted imaging was used to observe hematoma and perihematomal edema.Results On day 1 after modeling,the blood pressure was decreased significantly compared to that before modeling,and it was elevated gradually on day 3.Parallel profile test showed that the overall profile was parallel between the change rate of blood pressure and the change rate of perihematomal edema volume (F =2.820,P =0.063).The coincident profile test showed that both the overall profiles did not coincide (F =10.961,P =0.000).The change rate of systolic blood pressure was significantly positively correlated with the change rate of perihematomal edema volume (r =0.527,P =0.024) and the change rate of perihematomal edema volume (r =0.755,P =0.000) showed a significant positive correlation.Conclusions Brain edema appeared and expanded rapidly on the day of intracerebral hemorrhage in SHRs.It reached the peak on day 3,and then dissipated gradually.The blood pressure decreased significantly on day 1 after intracerebral hemorrhage,and it began to increase from day 3 till day 7.The changing trends of the blood pressure and perihematomal edema volume were parallel to each other,and the change rate of systolic blood pressure and the change rate of perihematomal edema volume showed a positive correlation.