Polymyalgia rheumatica (PMR) and exacerbated pulmonary fibrosis presented concurrently in a 69-year-old woman with a 5-year history of idiopathic interstitial pneumonia. The radiographic and histological examinations suggested usual interstitial pneumonia (UIP) as a more likely diagnosis. Corticosteroid therapy resulted in relief of the patient's muscle symptoms and improvement in the functional and radiographical signs of the pulmonary fibrosis. The final diagnosis was pulmonary fibrosis associated with PMR, because PMR is believed to be one of the causes contributing to interstitial lung diseases.