Clinical history and wedge biopsy specimen findings of a Vietnam veteran suffering from progressive severe tissue damage of lung are presented. The patient served as a soldier in defoliated areas for 2 years and developed severe chest pain and dyspnoea with chronic postnasal dripping, maxillary sinusitis and allergic asthmoid bronchitis with pronounced obstructions and eosinophilia. Recurrent onsets of symptoms over a period of 10 years led to wedge biopsies of the left upper lobe, right lower lobe and mediastinal lymph node. Histology is consistent with chronic, slightly progressive diffuse alveolar damage including moderate interstitial fibrosis. Total destruction of mediastinal lymph node with deposits of amorphous material and foreign body giant cells were noted. Histology findings and clinical course favor hypersensitivity reaction of lung and congestion of exogeneous material probably related to exposure to herbicides.