Overall leukocyte counts decrease during certain forms of hemodialysis, but little information is available on the intradialytic evolution of phagocytic metabolic function, especially during dialysis with dialyzers not affecting the number of circulating phagocytes. This study evaluated the phagocytic capacity of granulocytes and monocytes to generate CO2 out of glucose under basic unchallenged conditions and after stimulation with latex or zymosan, before and after 15, 60 and 240 minutes of dialysis with reused cuprophan, AN69S, polysulphone, polymethylmethacrylate and hemophan hemodialyzers. Phagocytic metabolic function was assessed in whole blood on the basis of 14CO2-production from labelled glucose during the phagocytic process. There were no changes in basic unchallenged CO2-production with any of the dialyzers. Reactivity to latex and zymosan, expressed per number of phagocytes, showed no decrease, irrespective of the membrane type. For polymethylmethacrylate and reused cuprophan, a slight but significant increase in metabolic reactivity was observed in response to latex and zymosan. The test employed may give a screening picture of the phagocytic reaction to contact with dialyzers and membranes and thus of their degree of biocompatibility towards the phagocyte system.