OBJECTIVE Patent blue vital (PBV) dye is used for varied perioperative indications, and has a potential for causing life-threatening allergic reactions. In this retrospective case series study, at a tertiary level neurosciences centre, we analysed the nature, management and outcome of adverse drug reaction to the preoperative use of PBV for marking vertebral level prior to back surgeries. METHODS Patients were identified from the theatre and radiology database. Data were collected from the patients' notes retrieved from the medical records division. RESULTS Eleven of 1247 (0.88%) patients experienced adverse reactions: 6 (0.48%) patients had minor grade I reactions (urticaria, blue hives, pruritis or generalised rash), 4 (0.32%) had grade II reactions (transient hypotension/bronchospasm/laryngospasm) and grade III reaction (hypotension requiring prolonged vasopressor support) was noted in 1 (0.08%) patient. No mortality was seen. The time of onset (range 10-45 min) frequently coincided with induction of anaesthesia or prone positioning of patient. Seven (63.6%) cases were cancelled or postponed (range 2-63 days). Treatment varied independent of the grade of reaction. Allergy workup (often incomplete) was done for 6 (54%) patients. CONCLUSIONS An awareness of the time of onset and infrequency of life-threatening reactions to patent blue dye may result in better management, less postponement, more complete workup and referral of these events.