Abstract: Objective To explore the changes and clinical significance of the thyroid hormone levels in elder patients when they are sick and after the illness. Methods 97 cases of elder in-patients without thyroid diseases were selected in this study. The serum levels of T3, T4, FT3, FT4 and TSH in patients at first day of in hospital and two months after the illness were detected. The blood sugar and blood fat levels were also determined. Results The serum levels of T3, T4, FT3 and FT4 in 97 cases of elder patients had significantly difference between sickness in the hospital and after the illness (P<0.05), but no significant differences in the TSH levels (P>0.05). Conclusion This research indicates that the thyroid hormone levels in elder patients when they are sick in hospital are significantly lower than that of after the illness.