Acute inhalation of organic dusts such as cotton, hay, silage, grain, animal confinement, or compost dust can result in illness characterized by fever, pulmonary inflammation, chest tightness, and airway obstruction. These agricultural materials are complex mixtures of plant, bacterial, and fungal products. Elucidation of the time course of disease onset, the mechanisms of disease progression, and the identity of etiologic agents is essential for effective prevention and treatment. Toward this end, animal models for acute organic dust-induced reactions have been developed and characterized. Information concerning the applicability of various animal models to humans and progress toward elucidation of causative agents and mechanisms of action is presented.