The textile industry is one of the oldest and second largest industries in the world. So, power loom provides a major source of employment to the rural people in India. The power loom workers can be exposed to dust, generated from the textile products in various stages during the textile manufacturing process. Numerous epidemiological studies have documented decrements in pulmonary function and various other health problems associated with long-term air pollution exposure. obesity is also an major cause which affects the pulmonary function periodically .Obesity can also affects the thorax, diaphragm and abdominal muscles which alters respiratory function even if the lungs are under normal circumstances. The study was designed to compare Body mass index with peak expiratory flow rate among power loom and non power loom workers in rural area in Salem district. 500 subjects between the age group of 30-70 years who volunteered to enroll for the study were selected. It included 250 power loom workers and 250 non power loom workers in a rural area in Salem district. Body mass index were measured by height and weight of the subjects. Peak expiratory flow rate was measured by using Wrights peak flow meter. The result shows as BMI increased PEFR decreased in both Power loom and non Power loom workers. But comparison with non power loom workers, PEFR was further more decreased in power loom workers when compared to non power loom workers which was statistically significant. Obesity may also cause impairment of diaphragmatic activity-dependent respiratory function. The mechanical behaviour of the respiratory system in obese individuals may altering lung volume, airway calibre or respiratory muscle strength.