The C282Y mutation of the HFE gene has been reported to be present in most of the patients with hereditary haemochromatosis (HH) of Northern European ancestry. HH affects approximately 1/300 individuals, but it is not evenly distributed in the different European countries. In the present study, polymerase chain reaction (PCR) and restriction-enzyme digestion were used to analyse the frequency of the most important mutation in haemochromatosis (C282Y) in subjects from Majorca (Balearic Islands, Spain) and patients with haemochromatosis. The results were compared with other studies from Spain and Europe. A total of 420 Majorcan chromosomes were analysed and the C282Y mutation was observed at a frequency of 2.62%+/-0.8 (11 heterozygotes: eight men and three women). In the group of hereditary haemochromatosis probands, 13 out of 14 were homozygous for the C282Y mutation. In the distribution of the C282Y mutation, a north-west to south-east cline was detected, supporting the Celtic origin of this mutation.