The purpose of this study is to evaluate the safety and tolerability of FG-3019, a therapeutic antibody designed to block the pro-fibrotic activity of connective tissue growth factor (CTGF). CTGF triggers the production of collagen and fibronectin, which cause scarring and thickening of the lungs. Approximately 18 to 27 males and females, 21 to 80 years of age with a diagnosis of idiopathic pulmonary fibrosis (IPF) will be enrolled in this study. The duration of the study is approximately one month, during which patients will receive a single infusion of FG-3019. In addition, there will be two follow-up visits 6 and 12 months after receiving the study drug.

Inclusion Criteria:

• are 21 to 80 years of age
• have a diagnosis of IPF by surgical lung biopsy or according to the American Thoracic Society criteria

Exclusion Criteria:

• have a history of significant exposure to organic or inorganic dust or drugs known to cause IPF
• have interstitial lung disease other than IPF
• have pulmonary fibrosis associated with connective tissue disease
• have other forms of idiopathic interstitial pneumonia, such as desquamative interstitial pneumonia, acute interstitial pneumonia, nonspecific interstitial pneumonia, or cryptogenic organizing pneumonia
• have end-stage IPF (total lung capacity of less than 45% of predicted value)
• are listed for lung transplantation at the time of study enrollment
• have significant heart problems
• are pregnant or lactating (if female)