Fischer-344 rats were exposed to 0.0, 0.3, 1.0, or 2.0 mg Cd/m3 as CdCl2 aerosol for 6 h/d, 5 d/wk, for 62 exposure days. Exposure to 2.0 mg Cd/m3 resulted in rapid weight loss, and all of the animals died within the first 45 exposure days. As a group, female rats survived significantly longer than the males. Exposure to Cd resulted in dose-dependent increases in lung weight. The increased weight was the result of additional tissue mass rather than edema. Both connective-tissue components, elastin and collagen, were significantly increased in the 1.0-mg/m3 group when these components were expressed on the basis of dry weight. Dose-dependent changes at the terminal bronchioles consisted of hyperplasia and flattening of type II cells, inflammation, and the proliferation of fibroblasts. Exposure to Cd also resulted in the development of intralymphatic microgranulomas in the perivascular and peribronchiolar lymphoid tissues.