Four hundred and six white caucasian patients with diabetes mellitus (243 male, mean age 54 +/- 16 (SD) years) were screened for haemochromatosis. Four patients had a fasting transferrin saturation > 62% and all were HLA A3 positive. Two were probable homozygotes for haemochromatosis and two heterozygotes. Homozygote haemochromatosis prevalence in this diabetic population was therefore 2/406 (0,0049) which is identical to that reported in the general population. These findings do not support a genetic relationship between the two conditions.