In order to elucidate the pathology and mechanism of lung toxicity induced by chronic hair spray inhalation, male Wister rats 9 wk of age were exposed to a uniform concentration of hair spray for up to 12 wk using a jet nebulizer. The aerosol concentration to which the rats were exposed was about 7 g/m(3). Differential cell counts in bronchoalveolar lavage fluid (BALF), the expression of several cytokines from alveolar macrophage using the reverse-transcription polymerase chain reaction (RT-PCR) method, and histopathologic evaluation using a computer-aided graphic analyzer (IBAS) were conducted 1, 4,8, and 12 wk after exposure. Over the passage of time, neutrophils and macrophages increased in BALF, and neutrophils infiltrated in the lung interstitium from the peribronchial interstitium to the alveolar septum. Alveolar macrophages showed increased expression of both the mRNA of tumor necrosis factor (TNF)-alpha and the mRNA of the chemokines macrophage inflammatory protein 2 (MIP2) and cytokine-induced neutrophil attractant (CINC). From these findings, chronic inhalation of hair spray is considered to induce at first intra-alveolar accumulation and activation of alveolar macrophages, followed by recruitment of neutrophils in the lung through the expression of proinflammatory cytokine, CINC, and MIP2, which cause predominantly neutrophilic inflammation in the lung.