Objective: Idiopathic pulmonary fibrosis (IPF) is associated with increased risk of lung cancer. The prevalence of high grade dysplasia/lung cancer was studied only in a small number of IPF patients. The aim of our study was to investigate the prevalence of precancerous/cancerous changes and their relationship with both metaplastic changes and clinical data. Method: Native lungs from 66 IPF patients were studied. The degree of honeycomb changes and squamous, cuboidal and bronchial cell metaplasia were graded (score: 0-3). The presence or absence of precancerous/cancerous changes were also evaluated. Results: Three patients showed neoplastic transformation (4 %) and nine high grade dysplasia (14 %) ("cancer" group). The "cancer" group had similar smoking history, sex, age and duration of disease than the "no cancer" group. All lungs showed metaplasia, the score of squamous (p= 0.0001), cuboidal (p=0.018) and bronchial cell (p=0.018) metaplasia was significantly higher in the "cancer" than in the "no cancer", while the honeycomb score was similar in the two groups. Conclusion: Advanced IPF patients have a high prevalence of high grade dysplasia/lung cancer, complex epithelial metaplasia, particularly squamous type, is more frequent in "cancer" group, independently from all clinical parameters, including smoking history.