A Cuban family carrying the α-chain variant haemoglobin G Philadelphia has been found during the course of a screening carried out at the Pediatric Hospital William Soler of Habana. Carriers of this abnormal haemoglobin which is present in high percentage showed also red cell abnormalities and a low osmotic fragility. The data presented in this paper support the hypothesis that the gene for the haemoglobin G α-Philadelphia is linked with a gene for α-thalassaemia.