Abstract: Serial observation of the correlation between the clinical manifestations and the plasma TXB₂ level was made in 30 cerebrovascular occlussive patients.21 males and 6 females with mean age of 60.Their lessions,for 5 cases in which they were located in vertebro-basilar system, were mostly in the internal-carotid system.The diagnosis was proved by brain CT scanning, cerebral angiography and CSF examination.Serial radio-immunoassay was used to detect blood plasma TXB₂ level.The results showed that the seveier the clinical course,the higher is the plasma TXB₂ value.Clinical serial observation showed that the cure rate was lower（37.5%）in cases of TXB₂-increasing type,and that in the decreasing type was much higher（76.4%）.In cases without any changes of the plasma TXB₂,mostly did not show apparent improvement.Therefore, the plasma TXB₂ level is not only closely related to the therapeutic results,but also is an important index for predicting the clinical fluctuation and estimating the prognosis. In 4 patients with cerebral hemorrhage,although their plasma TXB₂ value was higher no definite correlation between the clinical course and the plasma TXB-2 level has been observed.