Chorionic villus sampling (CVS) is a first trimester alternative to amniocentesis for the prenatal detection of genetic disorders. Initial experience in 48 patients, in whom transcervical CVS was utilised for the diagnosis of chromosomal, biochemical or molecular disorders, is reported. An adequate villus sample was obtained in all cases and a diagnostic result was achieved in 90% of cases. In this series, the miscarriage rate was 4.2%. It is concluded that CVS appears to be a relatively safe and reliable procedure, but the risk of miscarriage can only be accurately assessed after further investigation.