【Abstract】 Objective To study the correlation between clearance of asymmetric dimethylarginine (ADMA) by hemodialysis and nitric oxide (NO) production in maintenance hemodialysis patients (MHD). Methods Serum ADMA and NO productions (NOx) were measured in 159 MHD patients before and after the dialysis, from which the clearance of ADMA and NOx after the 4-hour dialysis treatment can be calculated. Samples from 20 healthy individuals were used as the controls. Serum ADMA and NOx before and after dialysis were compared. The comparison was also made in MHD patients and normal controls, MHD patients older than 65 years and those less than 65 years, MHD patients with diabetes and those without diabetes, and MHD patients with hypertension, hypotension, and stable blood pressure. Correlation analysis was performed to serum ADMA and NOx before and after the dialysis. Results In MHD patients after the dialysis, serum ADMA decreased[ (1.05±0.67)umol/L vs (0.83±0.53) umol/L, P＜0.001], and serum NOx increased [(61.1±38.5) umol/L vs (96.1±58.1) umol/L, P＜0.001]. The clearance of ADMA and NOx after 4-hour dialysis ranged (9.15±4.70) umol and (448.62±58.59) umol, respectively. MHD patients had higher serum ADMA before dialysis [(1.05±0.67) umol/L, P =0.002] and after dialysis [(0.83 ±0.53 umol/L, P = 0.004], as compared with serum ADMA of normal controls (0.35±0.06umol/L). However, MHD patients had relatively unchanged serum NOx before dialysis [(61.1±38.5) umol /L, P = 0.596] and after dialysis [(96.1±58.1) umol/L, P = 0.166], as compared with that of the normal controls [(68.1±13.6) umol/L]. Among the subgroups of HMD patients, no significant differences in serum ADMA and NOx were detected before dialysis, but negative correlation was found between serum ADMA and NOx before the dialysis (r = -0.344, P = 0.047) and after dialysis (r = -0.612，P = 0.001). Conclusion In HMD patients before dialysis, serum ADMA increased, and serum NOx was similar to the value of normal controls. Hemodialyis is capable to remove ADMA and NOx, although the clearance of ADMA is insufficient. The increase of serum NOx after dialysis may result from the removal of ADMA.