The outbreak of influenza in a corrections facility occurred during August 2000. The outbreak progressed following introduction of the disease by a member of the public to the facility. Rapid diagnosis and typing of the influenza isolates was available, although two prisoners required hospital admission due to the severity of complications at the time of diagnosis. The group demonstrated rapid transmission of the virus by the respiratory route and probably by fomites. The identified infecting virus was A/Moscow-like, an H3N2 subtype typically associated with large outbreaks. Prevention of such outbreaks will involve either achieving high rates of vaccination within the risk groups, or rapid (possibly point of care) diagnosis with the institution of antiviral therapy within 48 hours of symptoms. Influenza control within institutions is feasible using such strategies, although it requires considerable planning to have such approaches in place during winter--a time when institutional staff absenteeism is typically high.