Intensive immunization efforts in the United States have significantly reduced the incidence of reported rubeola; consequently, the report of an outbreak of rubeola among adolescent boys in one gym class in a Los Angeles high school was regarded as highly unusual. When all the boys had been seen and the spectrum of disease reviewed, rubella was considered the most likely diagnosis. A prodrome characterized by upper-respiratory tract symptoms was present in 65% of the ill students. The rash lasted more than five days in 32%. Recognition of the atypical manifestations of rubella in older age groups may serve to alert physicians to the presence of rubella in the community. With this knowledge, immunization efforts can be directed where they are most needed in an attempt to lessen the impact of the predicted rubella epidemic.