Approximately 700 hemoglobin variants have been reported, causing a variety of clinical manifestations, with the majority being clinically silent. We report a new hemoglobin variant, Hb Cook, that was found in combination with Hb E in a child of Thai origin. DNA sequencing of the beta-globin gene showed that the mutation is AAA-->ACA in codon 132, corresponding to beta 132 (H10)Lys-->Thr.