The two most common thyroid diseases are hypothyroidism and hyperthyroidism. Leptin is one of the most important adipose derived hormones. Leptin carries the message that fat reserves are sufficient. BMI represents an index of an individual’s fatness. Serum immunoreactive leptin levels show a strong positive correlation with body fat and Body Mass Index. The hospital based case–control study was conducted on 80 individuals including 50 known cases of thyroid disorders and 30 age and sex matched controls. Blood samples were estimated for serum leptin levels. BMI was measured using Quetelet’s index.The correlation between S. Leptin and BMI was positive in both in study as well as control group .On statistical analysis, p value came out to be extremely significant both in study and control group. Clinician should be particularly alert to the possibility of thyroid dysfunction in obese patients.