Relative risk of hyperparathyroidism and uremic iching in patients hemodialyzed by HF dialyzer is 0.51 (0.23 - 1.1) CI 95% and 0.85 (0.47 - 1.5) CI 95%, respectively Conclusions: Reduction ratio of low molecular weight uremic toxins such as ure, creatinin, P dialyzed by LF and HF dialyzer is similar.