The presence of Hb New York was confirmed in a Chinese family in which affected members have occasional red cells with Hb-H-like inclusions and a relative decrease in alpha chain synthesis, suggestive of a coexisting alpha thalassaemia trait. However, globin gene mapping and DNA hybridization revealed no deletion of the alpha genome. Timed-incubation experiments showed that the rate of synthesis of beta NY chain was greater than that of normal beta chain in the early periods. Chromatographic separation of Hb NY and Hb A before chain analysis revealed preferential binding of newly synthesized alpha chains to beta NY, with a four-fold increase in specific activity of the alpha Hb NY chains. It is concluded that beta NY chain is being synthesized more rapidly and its increased turnover may account for this presentation of apparent alpha chain deficiency.