A number of separate studies were performed: 1. Iron stores and HFE genotypes of 180 recipients of orthotopic liver transplants were assessed and liver biopsy specimens were graded for tissue iron deposition. Correlation was sought between HFE genotypes and iron measurements as well as length of stay in the transplant unit after initial transplant procedure; 2. HFE genotypes were analysed for a population of 351 individuals identified as iron deficient and compared with genotype results from a control population of 521 individuals with no full blood count evidence of iron deficiency; 3. Correlation between iron stores or HFE genotype and the severity of coronary artery disease was assessed in a population of 286 patients undergoing coronary angiography; and 4. A postal questionnaire was sent to 540 general practitioners to assess their level of awareness of hereditary haemochromatosis. Results: The feasibility of using the MADGE system to facilitate rapid HFE genotyping of relatively large numbers of samples was demonstrated. The prevalence of HFE genotypes in these studies correlated well with that reported for comparable populations in the literature. No evidence was found to support the theory that heterozygosity for the C282Y mutation can protect against the development of iron deficiency. There was no evidence of a correlation between increasing iron stores or HFE genotype and coronary artery disease in the population studied and no influence of HFE genotype on the outcome after orthotopic liver transplantation was identified. The questionnaire to general practitioners revealed a great variation in individuals’ awareness of hereditary haemochromatosis.