During mass campaign for measles/rubella vaccination on December 2003 in Iran, many pregnant women have vaccinated mistakenly. These women were grouped to susceptible and immune against rubella before vaccination by the status of IgG avidity response to rubella vaccine, then susceptible women were followed up to delivery time and their neonates were followed up to one year. In five neonates that were born from susceptible women, rubella-specific IgM has detected in cord blood sera, but they have not shown signs compatible to congenital rubella syndrome.