In our study of 52 patients with idiopathic pulmonary fibrosis (IPF), we found that the incidence of clubbing of the fingers was significantly more frequent in male than in female patients and in patients who showed lesser grades of honeycombing and higher grades of smooth-muscle proliferation in the pulmonary fibrotic changes (p < 0.01). Smooth-muscle proliferation in fibrotic changes of open lung biopsy specimens correlated with the mode of detection of IPF and the presence of clubbing of the fingers, duration of symptoms of the lower respiratory tract, and a higher extent of pulmonary infiltrates on chest radiographs (p < 0.05). However, the presence of clubbing of the fingers or grades of smooth-muscle proliferation in the pulmonary fibrotic changes did not correlate with the 2-year survival after open lung biopsy.