Peritoneal exudate macrophages collected from 4-wk-old broilers were capable of in vitro bactericidal activity against Escherichia coli and fungistatic activity against Candida tropicalis. Bactericidal activity was inhibited by treatment of macrophages with 2-deoxyglucose. These assays may be used to evaluate macrophage function in normal, diseased, and immunomodulated birds or to assess the direct effects of cytokines and toxins on macrophage microbicidal activity.