A dot-immunobinding assay for cytomegalovirus antibody in serum has been developed using a nitrocellulose sheet as the solid support and a protein A-horseradish peroxidase conjugate. Bound conjugate was detected using a para-iodophenol enhanced luminescent assay. Light emission from the glowing dots on the membrane were recorded using high speed instant photographic film (ASA 20,000). Photographic results of CMV antibody assays were assessed visually by comparison with results of standards run on each membrane.