A Celtic origin for hemochromatosis, a common genetic iron metabolism disorder, has been postulated for a long time. To check whether the two mutations recently identified in the HLA-class I candidate gene for this disease were found only in Caucasians, we examined their frequencies in individuals originating from Algeria, Ethiopia, and Senegal. The presumably disease-causing mutation, responsible for the Cys282Tyr substitution, was not found in any member of these ethnic groups, although it was shown to be highly prevalent in populations of European ancestry. This geographic distribution supports the previously suggested Celtic origin for the disease. In contrast, the mutation responsible for the His63Asp substitution is not restricted to European populations. Although absent in the Senegalese, it was found on about 9% of the chromosomes of the Central Ethiopians and Algerians (Mzab) genotyped for this study. This second mutation, which probably represents a common variant unrelated to hemochromatosis, thus appears to have occurred earlier than that responsible for the Cys282Tyr substitution. More detailed population studies are needed to provide information on the age of these two mutations and eventually show how the hemochromatosis-causing mutation chronologically spread throughout Europe.