During a one-year survey of a children's residence housing 20 young children and employing 29 adults, a confirmed outbreak of type C influenza unassociated with other known respiratory infections was studied. Seventeen of 20 children and two of the nine employees studied developed symptoms, which were characterized primarily by fever and nasal discharge. The three children who did not contract the disease were all under three months of age. Thirteen strains of virus were recovered from throat-swab specimens: 12 from children and one from an adult. All isolates were identified serologically as type C influenza virus. Evidence of reinfection was found in a two-year-old child and two adults who developed increases in antibody titers; the virus was recovered from a throat-swab specimen from one of these adults.