Results of routine rubella hemagglutination-inhibiting antibody tests on 39,005 serum samples showed that 9-5% of women of childbearing age in the Leeds region were seronegative, and a further 9-2% had low antibody titres of 1/8 or 1/16. Since routine rubella vaccination of schoolgirls began in 1970 the frequency of seronegative women in the fifteen to nineteen year age group has fallen by 5-7%. Clinical rubella was confirmed serologically in 140 women, 58 of whom were pregnant. 30 of these pregnancies were terminated, 2 resulted in spontaneous abortions, and 26 proceeded to term. One infant had congenital rubella.