Hypoplastic left heart syndrome was diagnosed prenatally and confirmed in 105 fetuses since 1983 at a regional referral centre. An increased detection rate since 1988 is probably related to increased experience in the use of a four-chamber view of the fetal heart during routine obstetric ultrasound scanning. When the diagnosis was made sufficiently early, most parents chose to terminate the pregnancy after the prognosis and surgical options were explained. By contrast, after an increase in the mid 1980s, since 1988 there has been a striking fall in the number of newborn babies with hypoplastic left heart syndrome treated at a supraregional referral centre. More widespread use of four-chamber cardiac screening during routine fetal ultrasonography may reduce the number of newborn babies with hypoplastic left heart syndrome--a factor which should be taken into account when the likely requirements for neonatal cardiac transplantation facilities are calculated.