The invention provides methods of treating or preventing pulmonary fibrosis or idiopathic pulmonary fibrosis (IPF) by administering an anti-EphA3 antibody to a patient. Moreover, the invention provides methods of identifying a candidate for treatment with an anti-EphA3 antibody by evaluating BAL fluid for EphA3 positivity are also disclosed. The invention further provides methods of measuring the efficacy of treatment by evaluating the reduction of the disease markers of fibrosis in a pulmonary fibrosis or IPF patient treated with an anti-EphA3 antibody are also disclosed.