A 77-year-old man was admitted to our hospital. He had first noticed a cough, sputum production, and low-grade fever during the summer of 1988. He was diagnosed as having summer-type hypersensitivity pneumonitis (HP) in 1989 on the basis of positive findings of anti-Trichosporon antibodies in the serum and bronchoalveolar lavage (BAL) fluid and and in environmental provocation tests. Thereafter, he presented with re-exacerbation of his disease in summer every year. In 1995, he retired from his work at a moldy hotel and moved to another house to avoid the causative antigen completely. There was no recurrence for the following 5 years. He suffered from cough, sputum production, and dyspnea 4 months after returning to his previous moldy house in October, 2000. A chest CT scan showed peribronchial and subpleural honeycombing, ground glass opacities, and traction bronchiectasis. BAL demonstrated that the lymphocyte count had changed from 78.9% to 42.9% and the CD4/CD8 ratio from 0.39 to 4.07 in 12 years. Antigen avoidance and steroid therapy have improved his condition. However, he stayed repeatedly in his moldy house, and finally died from acute exacerbation in March, 2002. Postmortem examination demonstrated diffuse alveolar damage (DAD) superimposed on honeycombing in the lungs.