Abstract: Ｏｂｊｅｃｔｉｖｅ：To evaluat the ecorrelation between  decrease of blood pressure and concentrations of COMM domaincontaining protein 5 (COMMD5) in hemodialysis patients after parathyroidectomy (PTx). Ｍｅｔｈｏｄｏｌｏｇｙ：(1) Blood pressure and COMMD5 serum concentrations were measured before and after PTx. (2) Rat vascular endothelial cells were stimulated with COMMD5 recombinant protein, and protein of ANP and eNOS were detected by Western blot.Ｒｅｓｕｌｔｓ：(1) PostPTx blood pressure(BP) was lower than pre PTx level (Systolic BP 14058±2055 mmHg vs 14881±1814 mmHg，P<005 ；Diastolic BP 7548±1283 mmHg vs 8874±1092  mmHg，P＜00001)  (2) PostPTx serum COMMD5 concentration was higher than pre PTx[097（064179）ng/ml vs 065（043107）ng/ml, P=002]. (3) There was a correlation between the decreases in systolic BP and plasma COMMD5; r=-057, P =0000 7; the decreases diastolic BP was associated with plasma COMMD5, r=-036, P=0043 6. (4) In vitro,COMMD5 recombinant protein stimulated vascular endothelial cells for 24 hours, the expression of ANP protein was 239 times that of Control group, P=0017 9; the expression of eNOS protein was 270 times that of Control group, P= 0000 5.Ｃｏｎｃｌｕｓｉｏｎ：Serum COMMD5 level increased after PTx in HD patients, and COMMD5 upregulated expression of ANP and eNOS,which may participated in hypotension after PTx in these patients.