A case of Pneumocystis carinii pneumonia is presented. Following presentation a chronic alveolitis was uncovered, which was due to ultimately repeated and prolonged inhalation of sweets containing gum arabic. The diagnosis was confirmed by a trans-bronchial biopsy and by chemical analysis of centrifugation of the alveolar lavage deposit. After cessation of the inhalation the progress was satisfactory both in terms of clinical status and lung function measurement.