Isoelectric focusing was used to determine the frequencies of Gc subtypes in Icelanders. The gene frequencies observed were Gc1F = 0.107, Gc1S = 0.631 and Gc2 = 0.262. An Icelandic Gc variant allele (Gc Iceland) is shown to have a different isoelectric point from the variant allele Gc-Norway. Gc-Iceland has been detected in 3 unrelated individuals giving the allelic frequency of 0.004 in the Icelandic population. Studies of 65 mother-child pairs confirm the assumed three-allelic mode of inheritance.