Between 1983 and 1987, 62 out of 76519 pregnancies in 51 mothers had a positive miniaturised Treponema pallidum haemagglutination assay (TPHA) test--1 in 1234, or 0.81 per 1000 births. About two thirds of these mothers had syphilis and the remainder non-venereal treponematoses such as yaws or pinta. Antenatal screening identified 13 patients with previously unknown acquired syphilis, 11 of whom were given antibiotics during pregnancy. There were six fetal losses among the 62 TPHA positive pregnancies, but none had evidence of congenital syphilis. No live born child in this study group showed stigmata of congenital syphilis. It is concluded that despite the current low incidence of syphilis in the United Kingdom it is imperative to continue antenatal serological screening and to emphasise the importance of early adequate treatment of the infection.