An interscalene block for shoulder surgery provides excellent surgical conditions and is well received by patients. However, a combination of the sitting position, regional anesthesia, an awake patient, and a surgical procedure can result in another side effect, vasovagal episodes, which may lead to cardiac arrest in extreme cases. We experienced a case of 32-year-old male patient with a severe vasovagal episode that led to asystolic cardiac arrest 15 minutes after the changing to the sitting position under an interscalene block for shoulder arthroscopic surgery.