Composted swine manure was examined for the presence of antibacterial and antifungal activities. While commercial composts show some antibacterial activity composted swine manure demonstrated inhibitory activity against Gram-positive bacteria and fungi. Weaker inhibitory activity against Gram-negative bacteria was also detected in composted swine manure. It is likely that these antimicrobial activities are due to compounds produced by bacteria or fungi present in the composted swine manure. An antifungal compound of possible commercial and agricultural significance is present in composted swine manure. Antibacterial agents of the same significance are also present.