Hb Westmead orα2122(H5)His→Glnβ2 is one of the most common hemoglobin variants in Guangxi, a province in Southern China. Theα2-globin DNA sequence of a carrier for this variant was selectively amplified by the polymerase chain reaction and analyzed with the restriction enzyme Stu I. We found that this mutant globin was encoded at theα2 locus and that the CAG→CAG mutation at codon 122 created a new Stu I restriction site. It is easy to detect this mutation by these methods.