The use of blue dye alone is the first described technique for sentinel lymph node (SLN) identification in patients with cervical carcinoma. In this procedure, Isosulfan Blue (IB), Methylene Blue or Patent Blue is injected into each quadrant of the cervix. We present an anaphylactic reaction to IB in a patient who underwent a laparoscopic hysterectomy. Approximately 15 min after the dye injection, the patient developed hypotension (55/35 mmHg) with an increase in heart rate (120 beats/minute) and a decrease of pulse oximetry to 85%. She was treated successfully with ephedrine, adrenaline, and fluid administration. When sterile drapes were removed, blue urticarial rashes all over the body were detected. The operation was halted, and the patient was transferred to the intensive care unit (ICU). Almost 4 hours after injection of IB, she experienced a second attack of bronchospasm under mechanical ventilation. She recovered uneventfully and was discharged from the ICU. The patient was referred to a skin prick test which was positive for IB. SLN biopsy for cervical cancers may have an increased risk of anaphylaxis probability due to administered blue dyes. It is crucial that the medical staff involved in these procedures be aware of anaphylactic reactions. This case report highlights the necessity of close monitoring of these patients in both the intraoperative and postoperative periods.