Gypsum is a mineral dust consisting of calcium sulfate and is commonly used in building construction. We here report the first case of an acute calcium sulfate aspiration. An accidental avalanche of fine gypsum powder covered entirely a silo worker. He aspirated a large amount of gypsum powder without loosing consciousness. At admission to the emergency department the patient was breathing spontaneously and directly underwent emergency bronchoscopy. Acute tracheobronchitis was diagnosed. Remaining calcium sulfate was removed by aspiration without rinsing with additional water in order to avoid further exothermic damage to the bronchial mucosa from chemical reactions. He received steroid treatment and antibiotics, as well as bronchodilatative therapy in an attempt to increase mucociliary clearance. Within a month the patient was symptomfree without any residual radiological or functional impairment. This unusual aspiration accident is to our knowledge the first case report of an accidental calcium sulfate aspiration. Our treatment choice left the patient without residual pulmonary impairment.