The results of studies on the serologic responses to Afipia felis and Rochalimaea henselae in suspected patients for Cat Scratch Disease (CSD) are illustrated. This preliminary study performed using Indirect Immunofluorescence Assay, proved negative for A. felis and R. henselae in some patients and positive in others; in a few instances the test was positive for both organisms. Additional microbiological and serological studies are needed to clarify the exact role of these microorganisms in causing CSD.