The ketogenic diet has demonstrated good efficacy in children with pharmacologically resistant seizures. Relatively few serious complications have been reported in the more than 70 years in which the diet has been used. We report a child who developed acute pancreatitis and died. A 9-year-old girl had a seizure disorder with associated developmental delay owing to glucose transport protein deficiency. The ketogenic diet with medium chain triglyceride oil had been initiated shortly after diagnosis in infancy. She was not on anticonvulsants. She presented in coma with decreased respiratory effort and shock, requiring resuscitation. Investigations were consistent with pancreatitis. Despite fluid resuscitation and inotropic support, she had prolonged hypotension and acidosis. She subsequently had a cardiac arrest and died. A postmortem examination confirmed hemorrhagic pancreatitis. Hypertriglyceridemia is a risk factor for developing acute pancreatitis. The high fat content of the ketogenic diet often causes hyperlipidemia. The outcome for this patient raises concern regarding a potential consequence of the ketogenic diet.