A course of seven video lectures on pulmonary pathophysiology has been placed on the internet. This is a companion to the course on respiratory physiology available at http://meded.ucsd.edu/ifp/jwest/. That course dealt with normal respiratory physiology, and the new lectures are about the function of the diseased lung. The topics covered include pulmonary function tests, chronic obstructive pulmonary disease, asthma and localized airway obstruction, restrictive lung diseases, pulmonary vascular diseases, environmental or industrial lung diseases (with a short section on neoplastic and infectious diseases), and respiratory failure. Although it could be argued that PhD physiologists do not have a responsibility for teaching pathophysiology, collaborative teaching has become increasingly common in medical schools where, for example, a pulmonary block includes both normal respiratory physiology and some pulmonary pathophysiology. It is hoped that these lectures will be useful to physiologists in that setting.