BACKGROUND Varicella-zoster is a highly contagious DNA virus, transmitted by direct contact and respiratory droplets. An attenuated live-virus vaccine has recently become available and is of value for susceptible, nonimmunized people. As with other attenuated vaccines, such as measles, mumps and rubella virus, there is no evidence of transmission by those immunized, and it is generally recognized that these vaccines can be given to the close contacts of pregnant women. METHODS A 32-year-old woman at 39 weeks of gestation presented with generalized pruritic vesicles and pustules. Diagnosis of primary varicella infection was made and confirmed by serologic studies. The patient denied recent or past exposure. The only significant history that the patient could recall was her exposure to her two children, who were vaccinated with the varicella-zoster vaccine eight days prior to her admission but were asymptomatic. CONCLUSIONS This is the first report of a pregnant woman contracting the primary varicella infection from exposure to close contacts vaccinated with the varicella vaccine. It may not be as safe as previously thought for seronegative gravidas to be in close contact with people vaccinated with the varicella vaccine.