Introduction: The six minute walk test (6MWT) is a practical and reliable measure of exercise tolerance that is widely used to assess the functional status of the patients with a variety of cardiac and pulmonary diseases, including heart failure, pulmonary hypertension, and Chronic Obstructive Pulmonary Disease (COPD). Objective: To evaluate the reliability validity and responsiveness of the six minute walk test and to measure the minimal clinically important difference (MCID) in South Indian IPF patients. Methods: The study population consisted of 30 patients diagnosed as IPF. Six minute walk test distance and other parameters were measured at baseline and at 18 week interval using a standard protocol. Correlation coefficients were used to evaluate the association between six minute walk distance and measures of dyspnea using Borg Scale rate of perceived exertion and Quality of Life questionnaire using St George Respiratory Questionnaire. The distribution based method was used to quantify the MCID. Results: The relationship between 6MWD with dyspnea and St George Respiratory Questionnaire showed good reliability (coefficient = 0.69 p<0.05). There was strong correlation between increase in 6MWD and decrease in Borg Scale of rate of perceived exertion and also decreased St George Respiratory Questionnaire indicating improvement in quality of life. The calculated MCID was 15 m. The decline in 6MWD indicated the prognosis of the disease. Conclusions: The six minute walk test is a clinically helpful measure of status of the disease and the prognosis in South Indian patients with IPF.