In a 58-years-old white woman with ankylosing spondylitis, plane chest radiograph revealed bilateral reticulonodular shadowing. Parenchymal high resolution computarized tomography showed bilateral diffuse ground glass appearance and honey-comb opacities especially in the lower lobes. Her pulmonary function test revealed a moderate degree of restrictive lung disease, carbonmonoxide diffussion capacity of lung were diminished. Brochioloalveolar lavage and transbronchial lung biopsy did not show any specific finding. So, we excluded other causes of an interstitial lung diseases by open lung biopsy. We suggest that also diffuse interstitial lung disease should be thought in ankylosing spondylitis patients having pulmonary symptoms. © 2005 Elsevier Ltd. All rights reserved.