Objective: To determine the effect of mobile phone on Peak Expiratory Flow Rate in chronic mobile phone users. Methods: The study was conducted in the department of Physiology at Pt. B.D. Sharma PGIMS Rohtak, Haryana. Peak Expiratory Flow Rate was recorded by Wright’s Peak Flow meter in subjects of either sex in the age group of 18-40 years in chronic mobile phone users using it for more than 5 years for atleast 30 minutes in a day.Apparently healthy individuals without any systemic illness or drug allergywere taken as subjects. Firstly, all the vitals and basal parameterswere noted down and then the subject was asked to read on mobile phone for 10 minutes. After that, another reading of Peak Expiratory Flow Rate was taken. This procedure was kept constant throughout the study. Results: Peak Expiratory Flow Rate was found to be decreased significantly after using mobile phone in 48 subjects( 38 males, 10 females) who were chronic mobile phone users. PEFR was seen to be decreased from 368.54±60.441litres/min to 354.58±58.480litres/min which is statistically significant. Conclusion: Mobile phone has the tendency to affect Peak Expiratory Flow Rate in chronic mobile phone users.