Plasma endothelin-1 (ET-1) and calcitonin gene related peptides (cGRP) were studied by immunoradiological method in 60 hemodialysis (HD) patients. The results showed that: (1) Plasma level of ET-1 and cGRP were increased in the HD patients. (2) Plasma level of ET-1 and cGRP varied in different times of HD. (3) A significantly positive relation between plasma ET-1 and blood pressure (BP) existed in the HD patients, while a significantly negative relation between plasma cGRP and BP existed in the HD patients. The results suggest that ET-1 and cGRP are major factors which lead to BP changes in HD patients.