A 2 yr old female ball python (Python regius) was presented to the University of Georgia Zoological Medicine Service for evaluation of oral discharge. The snake was anesthetized for diagnostic imaging, a tracheal wash, and blood collection. Under anesthesia, blood was obtained via cardiocentesis with a 25-g needle using standard protocol. Immediately following blood collection, a swelling was noted in the region of the heart. The snake was unable to recover from anesthesia and the heart subsequently stopped based on doppler assessment. The cause of death at necropsy was determined to be acute cardiac tamponade secondary to hemopericardium, with no additional histologic lesions noted within the heart. This is the first report of cardiac tamponade following cardiocentesis in a snake without a diagnosed cardiopathy, suggesting that risk factors should be considered when performing cardiocentesis in this species.