This study describes three couples at risk for homozygous beta-thalassaemia in which one of the partners carried a short deletion beta-thalassaemia defect. Detection of short deletions in trophoblast DNA was accomplished by the very simple procedure of non-denaturing polyacrylamide gel electrophoresis. This method may be applied to detect beta-thalassaemia mutations due to deletion or addition of more than two nucleotides.