After US licensure of the Merck varicella vaccine for immunocompetent persons on 17 March 1995, the Advisory Committee on Immunization Practices finalized draft recommendations for varicella prevention in the public health sector. These recommendations call for routine vaccination of children at age 12-18 months with a single dose of the vaccine. Varicella vaccine preferably should be given to children at the same time they receive measles-mumps-rubella vaccine and may be given at the same time as other vaccines recommended at this age. Children ages 18 months to 12 years who have not been vaccinated as part of the routine schedule and who lack a reliable history of varicella should be vaccinated. Vaccination is desirable for persons > or = 13 years old without a reliable history of varicella. Special efforts should be made to assess the immunity of and to vaccinate susceptible persons who have close contact with persons at high risk for complications, including family contacts of immunocompromised individuals and health care workers.