We analyzed varicella surveillance data in Connecticut for 2001-2005, to describe the epidemiology of varicella in a highly vaccinated population after the introduction of varicella vaccine and to determine the number of preventable cases that had occurred during school-related outbreaks. Overall, the incidence of varicella did not change during the surveillance period. Vaccination rates among reported case patients increased, and the severity of infection decreased. An annual median of 2.5 cases/outbreak was identified as being preventable, with a majority of these cases being preventable by revaccination of previously vaccinated persons. Continued surveillance is needed in order to monitor changing trends in varicella epidemiology.