The effects of metals on alveolar macrophage function were studied in-vitro. Cadmium (7440439) (Cd), mercury (7439976) (Hg), nickel (7440020) (Ni), lead (7439921) (Pb), aluminum (7429905) (Al), iron (7439896) (Fe), and chromium (7440473) (Cr) were incubated with alveolar macrophages and effects on oxygen (7782447) consumption, glucose metabolism, lysosomal enzyme release, and release of antibacterial substances were determined. All metals inhibited the rate of oxygen consumption, the release of lysosome enzyme, and glucose metabolism by the macrophages. The metals substantially inhibited the release of antibacterial substances. Hg had the greatest inhibitory effect, followed by Ni, Cd, Pb, Al, Fe, and Cr, in that order. All metals reduced the rate of foreign body ingestion by the cells. The authors conclude that metals inhibit the release of antibacterial substances from alveolar macrophages and have adverse effects on other aspects of cellular function. One adverse effect of metal exposure may be an increased frequency of respiratory infection.