The sequence of the A gamma globin gene from the affected chromosome of an individual heterozygous for the G gamma beta+ type of hereditary persistence of fetal haemoglobin (G gamma beta+ HPFH) is reported. With two exceptions, it is identical to one of the two allelic A gamma globin genes already sequenced and there is therefore no change which could explain the absence of its expression in the face of the persistent G gamma globin expression which is a feature of this condition.