In order to gain understanding of some of the problems of genetic counseling for a severe recessive disease in England, a Greek Cypriot extended family including 87 living members and known to be transmitting a beta-thalassaemia gene was investigated for the extent and the sources of their knowledge about thalassaemia. 42% of members tested carried beta-thalassaemia trait: nearly half were already aware of this, but only 10% of the non-carriers were aware of their status. The study illustrated many of the difficulties in conveying accurate counselling to a whole community and the need for active involvement of all health workers, especially general practitioners. This study is also relevant to the approaching possibility of genetic counseling for cystic fibrosis.