In August 1983, during the course of a hemoglobinopathy survey in Shimane Prefecture, we found a slightly fast-moving abnormal hemoglobin by isoelectric focusing (1). Structural analysis of this hemoglobin demonstrated it to be identical to Hb Tacoma, possessing an amino acid substitution of Arg→Ser at the position ofβ30. Hb Tacoma is known as a slightly unstable hemoglobin variant detected at first in America (2) and then in the Soviet Union (3), Finland (4) and again in America (5). The fourth case in America was a double heterozygote of Hb S and Hb Tacoma. Thus this is the fifth case in the world and the first case in Japan.