To evaluate granulocyte function in uremia and hemodialysis we studied granulocyte adherence, an important step in chemotaxis. Our studies demonstrate that patients with severe impairment in renal function had normal granulocyte adherence (72.1 ± 21 vs. 72.9 ± 14% controls) while patients with end stage renal disease undergoing hemodialysis (45 ± 30%) had significant impairment (p < 0.001). Adherence worsened during dialysis (p < 0.001) but returned towards the abnormal baseline values at the end of the procedure. There was a significant correlation between adherence and potassium (r = 0.77; p < 0.05) and adherence and sodium-potassium ratio (r=-0.78; p < 0.05) before and after dialysis. Other factors such as changes in creatinine, urea nitrogen, osmolality, calcium, phosphorus or (H<sup>+</sup>) did not correlate with adherence. It is concluded that the abnormality in adherence is not the result of the basic disease process but a consequence of dialysis.