Twenty one patients with chronic renal failure on regular hemodialysis werestudied, divided into two groups; diabetic and non diabetic group. Both basal bloodflow and percent changes of skin laser doppler flowmetry were diminished in bothgroups compared to control group. An inverse relation was found between basalblood flow and serum phosphorus. It was concluded that serum phosphorus ispartially responsible for endothelial dysfunction in uremics in regardless to the etiology.