Introduction: Hypothyroid or Hyperthyroid state affects all the physiological systems including cardiovascular system, central nervous system, digestive system, blood, etc. Among all adverse changes, Body Mass Index (BMI) can also be affected in patients with thyroid disorders. Objectives: The present study was carried out to compare body mass index in newly diagnosed patients of hypothyroidism, hyperthyroidism and age and gender matched euthyroid subjects Materials and methods: The present study was carried out in 90 female subjects in the age group of 30 to 45. Diagnosis of hypothyroidism and hyperthyroidism was based on both clinical and biochemical criteria. Subjects were divided in euthyroid, hypothyroid and hyperthyroid groups with each group containing 30 subjects. BMI was measured in all the groups. Results: Hypothyroid group had significantly higher BMI as compared to euthyroid group. Hyperthyroid group had significantly lower BMI as compared to euthyroid group. Hypothyroid group had highly significant more BMI as compared to hyperthyroid group Conclusion: Hypothyroidism subjects are more prone to weight gain and obesity as compared to euthyroid subjects. Hyperthyroid subjects lose more weight as compared to euthyroid subjects. All thyroid disorders should be treated appropriately to maintain normal BMI, failing which the patient can suffer from other undesirable effects of weight gain or weight loss.