Haemoglobinopathies are a group of genetic disorders which are particularly prevalent among certain risk groups such as ethnic groups. Antenatal screening of potential haemoglobinopathy carriers allows early diagnosis for affected fetuses, leading to therapeutic intervention or termination. However, it has drawbacks such as screening costs and possible miscarriage as a result of fetal testing. This paper describes a model that allows the outcomes of a screening programme to be estimated for different risk groups. The model has been implemented as a computer package that can be used to inform decisions made by health care planners.