We report on a 13-year-old-boy who had been admitted to our hospital for dyspnea, hypoxia, and pulmonary infiltrates. The diagnosis of allergic alveolitis was based on history (provocation by exposure), lung function tests, bronchoalveolar lavage, and transbronchial lung biopsy. No specific allergen could be identified. Five courses of methylprednisolone pulse therapy (15 mg/kg on three consecutive days) stabilized the patient with normalization of lung function and blood gas analysis. Between pulses the boy returned to his home on a farm without relapse. It is estimated that the effect of a single pulse lasted for at least 2-4 weeks. We conclude that pulse therapy can be used instead of continuous therapy in this rare disease in childhood.