An indirect immunocolorimetric assay (ICA) to detect rubella virus infected cells by the naked eye was developed. This assay was as sensitive and specific as an indirect immunofluorescent assay (IFA), could detect as little as 10 plaque forming units (pfu) of rubella virus in the initial inoculum and could detect viruses from throat swabs. This assay detected infection with viruses of all nine rubella virus genotypes available for testing. It could be utilized for virus quantitation and a neutralization assay. In addition to detecting rubella virus infection, this assay also allowed us to confirm measles virus infection. This assay should be useful for virus isolation from clinical samples.