A 7 yr old female spayed domestic shorthair was evaluated for suspected lily ingestion and acute vomiting. The cat had vomited suspected lily plant material before presentation, and a nasogastric tube (NGT) was placed to continue to administer activated charcoal. The NGT was passed with sedation and limited restraint. To confirm placement, a single lateral radiograph was taken, which showed that the tube was in the trachea, bronchus, through the pulmonary parenchyma, and extending into the region of the craniodorsal retroperitoneal space. The tube was subsequently removed, resulting in a tension pneumothorax. Bilateral thoracostomy tubes were placed and attached to continuous suction. The pneumothorax resolved after 2 days, the thoracostomy tubes were removed, and the cat was discharged on day 3 after admission. To the authors’ knowledge, this is the first described pneumothorax complication with successful medical management secondary to routine nasogastric tube placement in a cat. This case report underscores the importance of preparedness for thoracostomy tube placement before removal of any NGT that has been confirmed to be placed through the pulmonary parenchyma.