In some patients compliance to subcutaneous desferrioxamine therapy is reduced because of allergic symptoms. Effective drug desensitization consists of bringing patients to tolerate the same mode of administration. We evaluated three thalassemic patients with severe allergies to desferrioxamine. Each patient received weekly three prefilled infusors with desferrioxamine 4 g/48 m1/48 h for s.c. therapy. Follow-up was performed for 12 consecutive weeks. During follow-up no allergic events were noted. The s-ferritin levels decreased from 2583 micrograms/l +/- 485 to 1916 micrograms/l +/- 275 (mean decrease 25.8%, p = 0.038). Compliance to the infusional system was excellent. Our results show that continuous infusion of desferrioxamine using a new infusional delivery system is effective in preventing allergic reactions and in reducing iron overload.