We describe the cases of an 18-year-old female and a 15-year-old male who developed severe anaphylaxis following contact of surgical wounds with the disinfectant Lavasept, containing polyhexanide, a polymerised form of chlorhexidine, during orthopaedic interventions. According to the manufacturer, this product is the only polyhexanide containing medical disinfectant, has recently been commercialised and is only available in Switzerland. One of the patients denied previous contact with this compound but both patients were previously exposed to chlorhexidine. Immediate-type hypersensitivity to polyhexanide was suggested by positive skin prick tests in the two patients and by negative skin tests in control individuals. Skin tests with chlorhexidine in the patients remained negative. We conclude that contact with the new disinfectant Lavasept can trigger anaphylactic reactions, even in the absence of previous history of exposure to this compound. It remains to be established whether this new disinfectant is a frequent anaphylactogen.