147 hemodialyzed patient were studied for the presence of allergic reactions related to the dialytic treatment. Total IgE and specific IgE to common inhalants, ethylene oxide and phthalic anhydride were determined in all patients. The same determinations were also performed in two control groups. Specific IgE to ethylene oxide were detected in 7 sera. Among these 6 had a high total IgE level and 2 had a positive Phadiatop. Only 3 among the 7 positive patients had adverse reactions related to the hemodialysis (one suffered from itching, one from urticaria and the third from angioedema and hypotension). The resolution of the symptoms was obtained utilizing a gamma-rays sterilized filter. Therefore ethylene oxide sensitization may be a cause of some problems during hemodialysis. We couldn't find a relationship between atopic status and sensitization to ethylene oxide in as much in only 2 out of 7 patients sensitized to ethylene oxide, specific IgE to common inhalants were detected.