Idiopathic pulmonary fibrosis is a chronic condition of the lung parenchyma involving progressive injury, inflammation, and fibrosis. Data collected from October 1988 through September 1990 in the population-based registry of patients with diffuse lung disease in Bernalillo County, New Mexico, suggest that the prevalence of this disease is roughly 20 cases per 100,000 men and 13 per 100,000 women.¹ Idiopathic pulmonary fibrosis has the highest mortality of all of the diffuse lung diseases. Mortality rates from the disease almost doubled in England and Wales between 1979 and 1988,² an increase that was not due to differences in the way the . . .