To evaluate potential role of serum leptin level in hyperthyroid female patients and find out its relationship with BMI. Atomic Energy Medical Centre and Basic Medical Sciences Institute, Jinnah Postgraduate Medical Centre, Karachi. Serum leptin, FT3, FT4, TSH, serum triglyceride, total cholesterol, HDL-C, LDL-C were determined in 30 newly diagnosed untreated hyperthyroid female patients and 22, age, sex and BMI matched lean control group (BMI 30). The female patients identified from thyroid OPD of AEMC, JPMC, Karachi, through thyroid profile results and sign and symptoms of the disease. The clinical history was taken and physical examination performed. A significant difference p