Five enzyme immunoassays for the detection of Epstein-Barr virus immunoglobulin M were evaluated versus indirect immunofluorescence assays with 128 serum specimens. The sensitivities and specificities, respectively, of these kits were as follows: Gull, 92 and 100%; Incstar, 53 and 100%; Ortho, 89 and 100%; Sigma, 78 and 86%; and BioWhittaker, 94 and 70%. Indeterminate results were produced by 2, 2, 0, 8, and 14 specimens with the Gull, Incstar, Ortho, Sigma, and BioWhittaker tests, respectively. The Gull and Sigma tests had the best day-to-day reproducibilities, and the Gull test was the easiest to use. No correlation between immunofluorescence titers and enzyme immunoassay values was observed.