A pool of seven monoclonal antibodies, each reactive with cytomegalovirus (CMV) early antigens, was used in an indirect immunofluorescence method for the rapid detection of CMV-infected fibroblasts following inoculation with clinical specimens. A total of 1,639 specimens were examined, and the results were compared with those of conventional isolation procedures. The detection of CMV by early antigen fluorescent foci (DEAFF) was found to be comparable, both in terms of specificity and sensitivity, to that of conventional cell culture. Its great advantage, however, is the rapidity with which results are achieved. Thus, results were available from the DEAFF test within 24 hours of receipt of the specimens as compared to a mean of 16 days for cell culture. This single rapid assay for the detection of CMV in clinical samples may be performed by any laboratory familiar with cell culture techniques and in our hands is the preferred diagnostic method for CMV.