We ?report a successful diagonsis and treatment of a 85-year old male patient with euthyroid sick syndrome (ESS). After thyroid dysfunction and other relevant factors leading to coma were excluded, basic treatment and thyroxine intervention therapy were adopted. The patient returned to normal state of consciousness. No adverse effects resulting from taking thyroxine was observed during the 2 years of follow-up. Because of reduced blood supply to the brain and more susceptible brain function due to various underlying diseases, elderly patients are prone to ESS. Appropriate thyroxine intervention therapy is beneficial to the outcomes of the disease.