Nitric oxide has been regarded as a marker of oxidative stress in various diseases. There is a lot of controversy regarding levels of nitric oxide in thyroid disorders. The present study included 50 diagnosed hypothyroid, 50 hyperthyroid and 50 healthy controls. The nitric oxide levels were estimated by Griess reaction. The results were compared statistically. Nitric oxide concentration was found to be significantly low in hyperthyroid patients (6.4±3.8 µmol/L) as compared to control subjects (36.24±7.61 µmol/L) (p < 0.05), while it was significantly raised in hypothyroid patients (57.6±15.8 µmol/L) (p < 0.001). Estimation of nitric oxide levels in thyroid disorders may aid in understanding the etiopathogenesis of thyroid disorders.