PURPOSE: Hypertension is a common problem in maintenance hemodialysis (HD) patients. We assessed the effects of low sodium dialysate on changes of blood pressure in maintenance HD patients. METHODS: Forty HD patients were enrolled in this cross-over study. All the patients underwent nine consecutive HD sessions with the dialysate contained 138 mEq/L sodium (conventional sodium HD), then concentrations of sodium were switched to match the patients average pre-HD plasma sodium measured during the conventional sodium phase (135 mEq/L for patients with sodium levels less than 137, 137 for patients with sodium levels over 137). Dry weight and dialysis prescription were not modified during the six weeks of the study. RESULTS: There was a significant decrease in the interdialytic weight gain (2.4+/-0.9 kg vs. 2.0+/-0.7 kg, p<0.001) and the interdialytic thirsty in low sodium HD sessions compare to conventional sodium HD sessions. Pre-HD systolic and diastolic blood pressure (BP), post-dialysis systolic BP was similar in both periods of the study. The use of low sodium dialysate is associated with significantly lower systolic BP in patients with uncontrolled hypertension (n=10,157.1+/-3.6 mmHg vs. 148.0+/-9.4 mmHg, p=0.011), but not in those with controlled hypertension. Cardio-thoracic ratio was significant decrease in low sodium dialysate HD (0.53+/-0.08 vs. 0.51+/-0.07, p=0.002). The episodes of intradialytic hypotension and related symptoms were not more frequent in low sodium dialysate HD. CONCLUSION: Low dialysate sodium concentration based on predialysis sodium levels of patients could reduce the pre-HD systolic BP, interdialytic thirsty and interdialytic weight gain in maintenance HD patients.