A 70-year old man was admitted to our hospital because of nonproductive cough, fever and increasing dyspnea associated with alveolar opacities on chest roentgenogram, which later migrated to previously unaffected areas. The diagnosis of Chlamydial pneumonitis was made on serological grounds. Organizing pneumonia was documented by transbronchial lung biopsies and the subsequent course was satisfactory under minocycline therapy. Chlamydial infection should be considered in the differential diagnosis of migratory pulmonary infiltrates.