Summary: Skin hypersensitivity to two isolated staphylococcal antigens, protein antigen A and teichoic acid, was demonstrable in all adult subjects. Immediate hypersensitivity was not correlated with the presence of or high titers of precipitating antibody. Delayed central necrosis following the injection of teichoic acid occurred only in subjects with high levels of antibody to teichoic acids. Release of a lysosomal enzyme, lysozyme, from leukocytes into supernatants occurred following incubation of these cells and high titered teichoic acid antibody with teichoic acid. The concentrations of antibody required for the greatest release of lysozyme were present infrequently in normal sera but were found frequently in patients with active staphylococcal diseases. In contrast the delayed skin reactions to antigen A were not correlated with the titer of serum antibodies. Release of lysozyme did not occur following incubation of antigen A and leukocytes with high titered human sera.