Background: In patients with a nephrotic syndrome, urinary losses of thyroid hormone and thyroid-binding protein are known to be associated with developing of hypothyroidism. However, a limited number of studies have reported accurate prevalence and relating factors of overt or subclinical hypothyroidism in nephrotic syndrome patients. Methods: In this study, retrospectively, we evaluated 79 patients were diagnosed nephrotic syndorme in Chosun University Hospital with thyroid function test. Result: There were 43 males and 36 females of 79 patients. Mean age was 49.9 years old. Serum creatinine concentration was 1.57 mg/dL and mean TSH level was 4.037 μIU/mL. The prevalence of subclinical hypothyroidism was 16.5% (13/79), over hypothyroidism was 13.9% (11/79) and euthyroidism was 69.6% (55/79). Serum albumin was significantly lower in the hypothyroidism patients compared with euthyroidism patients (p<0.05). 24hr proteinuria amount was lower in hypothyroidism patients than euthyroidism patients but no statistical significance (p>0.05). TSH was negatively correlated with serum albumin (r=-0.430, p<0.002) and positively correlated with 24hr urine protein amount (r=0.396, p<0.01) and 24hr albumin amount (r=0.340, p<0.01). We observed that TSH level was significantly normalized after 24hr proteinuria amount was controlled to normal range (p<0.05). Conclusion: Our study shows that the incidence of overt hypothyroidism was highly 13.9% and TSH level is a useful index in diagnosis and treatment of hypothyroidism in nephrotic syndrome patients.