Objective: The etiology of idiopathic interstitial pneumonias (IIPs) remains unclear. Many researches assumed that viruses can represent an important factor of aggression to the lung provoking fibrosis. In this regards, we researched the presence of virus infections in patients with IIPs. Method: Biopsy samples from 13 patients with idiopathic interstitial pneumonia (IPF); 8 patients with nonspecific interstitial pneumonia (NSIP); 13 patients with acute interstitial pneumonia (AIP) and 4 patients with idiopathic cetrilobular fibrosis (ICLF) were used to investigate by microarray and immunohistochemistry the presence of measles virus (MV), hepatitis-C virus (HCV), adenovirus (ADV), respiratory syncytial virus (RSV), Epstein-Barr virus (EBV), herpes I and II viruses (HVI and HVII). Results: We detected the epithelial alveolar infection by MV and CMV in 30.8 % and 15.4 % in AIP, respectively. Endothelial CMV infection was observed in 25 % of ICLF group. When we compared with the age of these patients, patients with ≤ of 43 years old had more infection by MV and CMV than the group with ≥ 72 years old. The other viruses were not detected in the different groups. Conclusion: The viral infections observed in AIP and ICLF groups reinforce the possible viral participation in these pulmonary diseases. Financial Support: FAPESP.