OBJECTIVE: To investigate the changes of serum thyroid hormone levels in children with the simple nephrotic syndrome.METHODS: We measured the serum thyroid hormone levels in a group of simple nephrotic syndrome children (n=20) and a group of healthy controls (n=20) by radioimmunoassay double antibody (RIA-DA), and then compared the differences in serum thyroid hormone levels the 2 groups by a statistical method. RESULTS: The thyroid hormone levels in the contorl group were normal, but the serum T 3, T 4, TSH in the nephrotic syndrome group showed changes of different degrees. They were (1.0 ±0.5) nmol/L, (15.5 ± 32.4) nmol/L, and (20.2±13.2 ) mU/L, respectively. There was a significant difference between the simple nephrotic syndrome group and the controls (P< 0.01). CONCLUSIONS: There might be some significance in using serum thyroid hormone levels in children with the simple nephrotic syndrome for the improvement of management, curative effect and evaluation of prognosis.