A 37-year-old woman who had developed diabetes insipidus after an abortion, requiring nasal substitution treatment with desmopressin (Minirin), began to suffer from fatigue, nocturnal sweating, cough and dyspnoea on exertion. Exogenous-allergic alveolitis was demonstrated by chest x-ray, lung function tests, blood gas analysis, broncho-alveolar lavage and transbronchial lung biopsy. After changing the treatment to an intramuscularly administered preparation and starting steroid therapy the clinical, radiological and lung function findings rapidly improved.