Hypersensitivity reactions might occur during anaesthesia. Muscle relaxants have the highest frequency of inducing anaphylaxis. Rocuronium is the most common out of all muscle relaxants. We experienced a case of anaphylaxis occurring due to rocuronium during anaesthesia in a patient who is coming for a nephrectomy at Queens Hospital, London, UK. We managed the episode of anaphylaxis according to guidelines established by Association of Anaesthetists of Great Britain and Ireland.