We report two cases of severe anaphylactic reactions to rocuronium. Diagnosis was confirmed by skin tests and specific IgE assay. Cross-reactivity to all neuromuscular blocking agents was investigated by intradermal tests and leucocyte histamine release test. Intradermal tests and leukocyte histamine release were negative for cisatracurium. The two patients had undergone a subsequent general anaesthesia using cisatracurium and did not present any adverse reaction.