Hemodialysis-induced hypotension in CRF (chronic renal failure) patients is a very common complication; however, the pathogenesis still remains unclarified. Amezinium methylsulfate (Risumic(R)) is an indirect, primarily alpha-sympathomimetic agent. We studied the preventive effect of amezinium methylsulfate on hemodialysis-induced hypotension in chronic hemodialysis patients. Twelve hemodialysis patients were enrolled in this study. They had been on hemodialysis longer than 3 months and had frequent episodes of hemodialysis-induced hypotension, which is defined as follows: 1. systolic blood pressure 90 mmHg or diastolic blood pressure 40 mmHg; or 2. decreased systolic blood pressure over 40 mmHg during hemodialysis; or 3. onset of the hypotension symptoms. After 2 weeks of observation period, patients received one tablet (10 mg) of Risumic(R) 30 minutes prior to every hemodialysis session for 1, 2, or 6 weeks. And then, they had 2 weeks of observation period. Mean arterial pressure (MAP) during every dialysis session was measured throughout the study period, and the mean of MAP was analyzed by unpaired "t-tist" (p<0.001) and by repeated measures ANOVA. MAP increased after medication, reaching the peak at 3 weeks after the medication start. The MAP increase was slightly reduced at 6 weeks to regain again and the MAP remained increased again until 2 weeks after stopping the medication. The overall increasing pattern of MAP however, through the study period was not statistically significant (p=0.215). This result shows that Risumic(R) seems to be useful to prevent hemodialysis-induced hypotension in chronic hemodialysis patients.