Timolol maleate is a beta-blocker widely used in topical administration for open angle glaucoma. We report a case of interstitial pneumopathy which developed in a 58-year-old patient who was given timolol eyedrops (2 drops b.i.d. since 1986). The patient presented with cough and dyspnea and was found to have a restrictive disorder leading to hypoxemia (68 mmHg at rest and 51 mmHg during exercise). Bronchial lavage fluid had high lymphocyte (28%) and neutrophil (7%) counts. Transbronchial biopsies demonstrated moderate fibrous thickening of the interalveolar walls. Timolol eyedrops were stopped. Three months later, the patient was asymptomatic with normal lung function, chest x-ray and thoracic CT-scan.