These experiment was carried out to investigate the pulmonary lesions and the function of alveolar macrophages in rats exposed to cement dusts. 1. The number of total cells in bronchoalveolar lavage fluid(BAL) increased remarkably in 1st month. As time goes by, tend to less and less in numbers. 2. The number of neutrophil and lymphocytes obtaining from the total cell of BAL increased remarkably in first month, but as time goes by, they tended to grow less and less in number. Macrophages decreased gradually after being temporarily augmentation. 3. Histipathologically, the thickening of alveolar walls, alveolar interstitial, and infiltrated macrophages containing cement dusts.