On a field trip to Saudi Arabia (M. A. F. E. H.) in which the relationship betweenα-thalassemia and iron deficiency was studied, a fast moving hemoglobin variant was noted in a 30 year old Saudi Arabian woman. Analysis of the hemoglobin variant showed that the amino acid substitution wasβ120 Lys-Asn. This variant had not been described previously and has been named Hb Riyadh. There was also present anα-thalassemia and details are given of the imbalance of globin chain synthesis. It was possible to improve considerably the balance in vitro by the addition of hemin.