A 52-year-old patient with Klippel-Feil syndrome was scheduled for elective C1 dorsal laminectomy and occipito-cervical stabilisation under general anaesthesia. Preoperatively she had bulbar symptoms and a history of recurrent aspiration pneumonia, but no evidence of cardiovascular disease. When she was turned prone she developed persistent tachycardia, hypotension and ST segment changes despite fluids, pressors and inotropes. Her condition improved when turned supine, but she had persistent ECG changes and a troponin rise was measured the following day. She was extubated two days postoperatively but aspirated again and subsequently died 12 days later from respiratory failure. If prone positioning is required in patients with Klippel-Feil syndrome we suggest meticulous positioning to avoid sternal compression of the heart. We also suggest thorough preoperative respiratory evaluation and elective postoperative intensive care as these patients are at high risk of developing postoperative respiratory failure.