The serum conversion rates and post-vaccination rubella haemagglutination inhibiting antibody titres of a group of women given both anti-D immunoglobulin and rubella vaccine in the puerperium have been compared with those of a similar group of patients who were given vaccine but no immunoglobulin. The serological response to rubella vaccination in susceptible women was satisfactory even when anti-D immunoglobulin was given shortly before vaccination.