The prevalence of hereditary haemochromatosis (HH) in Saguenay-Lac-St-Jean (SLSJ), a geographically isolated region of northeastern Québec, was estimated at 0.014; the heterozygote frequency was 0.21. These are among the highest frequencies found thus far in white populations. The fertility study completed in SLSJ showed that carriers of the HH gene tended to have more children than non-carriers. However, since these differences were not statistically significant, there appears to be no basis on which to accept that HH heterozygotes are at a selective advantage. Therefore, genetic drift cannot be excluded.