We report a case of bronchiectasis with marked thickening of the respiratory tract wall occurring in a 37-year-old man with UC and HAM. He was diagnosed as UC at age 20. HTLV-1 was presumably transmitted to this patient by means of a blood transfusion he received at around age 30. On admission, chest X-ray films, tomography and CT-scan revealed dilated lumens and thickened airway walls extending from the trachea to subsegmental bronchi. Pulmonary function tests showed hypoxemia and mixed ventilatory disturbance with a predominantly obstructive component. HAM was diagnosed on the basis of neurological examination and cerebrospinal fluid analysis. A biopsy specimen from the carinal mucosa showed marked T cell infiltration. In these T cells, we detected polyclonal integration of HTLV-1 proviral DNA. Some of the infiltrating T cells showed atypia. In recent times, respiratory diseases other than infiltration of adult T-cell leukemia cells or opportunistic infection have been reported in HTLV-1 carriers and new clinical entities designated as HABA (HTLV-1 associated bronchiolo-alveolar disorder) and HBA (HTLV-1 associated bronchopneumopathy) have been proposed. This case is classified among these new entities, in a broad sense, and is a rare case in that the respiratory disorder is apparently related to UC.