We present a pregnant developed cardiac arrest due to a severe anaphylactic reaction to i.v. sulbactam-ampicillin, who had no history of allergy to penicillin and cephalosporin. Ampicillin is one of the most common drugs to elicit a rash, with an overall incidence of 3% to 8%. Five to ten percent of people on ampicillin develop eruptions between the 5th and 14th day following initiation of therapy. The incidence of immediate hypersensitivity reaction or anaphylactic reaction to cephalosporin antibiotics has been estimated at 0.02% and most of these patients have a history of allergy to penicillin and/or adverse reactions to cephalosporins. We present a case of immediate systemic reaction to sulbactam-ampicillin in a pregnant women whom exposed to intravenous sulbactam-ampicillin several times in past. The patient manifested a severe reaction which included anaphylactic shock, requiring orotracheal intubation and epinephrine. In this case, we emphasized the importance of early, fast, effective,and proper cardiac resusitation for anaphylaxis which may improve the prognosis.