Effective treatment of hypotension during induction of general anesthesia depends onhow well the many causes of the hypotension are understood. However, differential diagnosis of hypotension is by no means easy, especially when the prevalenceof hypotension is low or when the patient is asymptomatic. A 75 year-old female, upon induction of general anesthesia for open thoracic surgery, became hypotensive and showed generalized erythematous papules, therefore having to postpone the surgery. Upon further evaluation through skin prick tests, the hypotensive event was concluded to be caused by anaphylactic side effects of atracurium. Hence, atracurium was avoided and the surgery was successfully performed.