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Introduction:The membranes used in haemodialysis may be manufactured from cellulose, modified cellulose or synthetic polymers. Such membranes, when in contact with blood will activate the complement system, which entails changes in leukocyte and platelet counts. Polysulfone is a synthetic membrane of high biocompatibility standards, whereas haemophane membranes are modified cellulose-based membranes. The biocompatible profiles of these membranes, has been studied by clinical reactions (i.e. hypotension, nausea, pruritis, …) during dialysis sessions. Both kinds of these membranes are used in Iran. The number and severity of these reactions define the degree of dialysis biocompatibility. Materials and Methods: In a clinical trial study which was carried out in Imam Khomeini hospital in Tehran, 100 hemodialysis patients were enrolled to this investigation. Their clinical reactions were compared during 3 sessions of hemodialysis with polysulfone and 3 sessions of hemodialysis with hemophan membrane. Each patient was the control of him/herself. Data was analyzed using Chi square test. Results:Mean age of patients was 48.85±17.56 years and 39% of them were female. The most common complications were hypotension and muscle cramps (each 21.5%). Hypotension was higher in sessions of polysulfon versus hemophane (18% versus 25%) but was not significantly different. Also other complications such as muscle cramp, nausea, vomiting, dyspnea, headache, chills and fever had no significant difference. Seizure did not occur in any patient. Conclusion: According to our findings the membrane’s type has no role in acute clinical complications during hemodialysis and in most patients, membranes can be used according to their availability. It seems their biocompatibility has no considerable clinical difference.