Diffuse panbronchiolitis (DPB) is an idiopathic inflammatory disease, largely restricted to Japan, that is characterized by progressive suppurative and obstructive airway disease, which, if left untreated, progresses to bronchiectasis, respiratory failure, and death. The lesion was first described in the early 1960s. In 1969 the name diffuse panbronchiolitis (DPB) was proposed to distinguish it from chronic bronchitis. Diffuse refers to the distribution of the lesions throughout both lungs, and pan refers to the involvement of inflammation in all layers of the respiratory bronchioles. Its distinctive imaging and histologic features, the coexisting sinusitis, and the isolation of Haemophilus influenzae and Pseudomonas aeruginosa in the sputum should enhance disease recognition. Neutrophils and T-lymphocytes, particularly CD8- cells, together with cytokines IL-8 and macrophage inflammatory protein-1 are believed to play key roles in the development of this disease. Significant improvement in the prognosis of this potentially fatal disease has been reported after the use of long-term therapy with macrolide antibiotics, the effect of which is attributed to an anti-inflammatory and immunoregulatory action.