Seven Chinese patients (5 males and 2 females) with vaccination-induced acute metabolic crisis were reported. Only one male with 21-hydroxylase deficiency had been diagnosed before vaccination. In the remaining six patients, the preexisting diagnoses were not confirmed before the vaccination. Acute metabolic crisis occurred in seven patients between 3 and 12 hours after the administration of Japanese encephalitis, diphtheria, and tetanus toxoids and acellular pertussis, hepatitis B, or measles vaccines. Patients 1 and 2 displayed acute adrenal insufficiencies at the ages of 5 years and 3 months, respectively. Patient 3 had presented with mild motor retardation previously. Patients 4 to 7 were previously healthy, but suffered from fever, seizures, coma, acidosis, and hypoglycemia after being vaccinated. Glutaric aciduria type 1 was evident in case 4. Leigh syndromes were present in Patients 5, 6, and 7. They all died from respiratory failure before 2 years of age. Symmetric foci, cystic cavitations with neuronal loss, and vascular proliferation were observed by postmortem examination. Among the seven patients, although the vaccines were not the primary cause of the acute metabolic crisis, the severe acute episodes occurred coincidentally.