Analysis of perinatal mortality attributed to congenital malformations in England and Wales, using data from birth and death registration over the years 1974-81 showed significant declines in England and Wales as a whole and in the individual Regional Health Authority (RHA) areas. A greater decrease in death rate from congenital malformations, particularly central nervous system malformations, was seen among stillbirths than among early neonatal deaths. There were marked regional differences in perinatal mortality due to central nervous system malformations over the period but not in cardiovascular system malformations or in other malformations. The highest mortality rates due to central nervous system malformations occurred in the North, North-West, West and South-West of England and in Wales, and the lowest rates in the South and South-East. The larger percentage reductions in the mortality rates were found in most of the regions which had had the highest rates. Possible explanations for the decline in regional rates are suggested.