Hereditary hemochromatosis is an autosomal recessive disorder, the gene for which occurs in approximately 10% of Americans, most of whom are unaffected heterozygotes. Approximately 5/1000 white Americans are homozygous and at risk of developing severe and potentially lethal hemochromatosis. The disorder affects numerous organ systems, but the most common symptoms are fatigue, palpitations, joint pains, and impotence; the most common signs are those that relate to hypothalamic, cardiac, hepatic or pancreatic dysfunction, including poor cold tolerance, impotence in males, amenorrhea in females, cardiac arrhythmias, dyspnea, edema, hepatosplenomegaly, spider telangiectases, ascites, deformity, swelling or limitation of motion of joints, weight loss, hyperpigmentation. Characteristic abnormalities of laboratory tests include elevated serum iron concentration, high transferrin saturation, elevated serum ferritin concentration, elevated serum transaminases, hyperglycemia and low values for thyroid-stimulating hormone (TSH) and gonadotropins. Death may be the result of cardiac arrhythmia, congestive heart failure, liver failure or liver cancer. Since many of these complications cannot be reversed once they have developed, early diagnosis and treatment are essential. In view of the high prevalence in the American population (prevalence varies with ethnic background), the low cost of diagnosis and treatment, the efficacy of treatment if begun early, and, on the other hand, high costs and low success rate of late diagnosis and treatment, systematic screening for hemochromatosis is warranted for all persons over the age of 20 years. The initial screening should be by measurement of serum iron concentration and transferrin saturation. The practice guideline provides a diagnostic algorithm for cases in which the serum transferrin saturation is 60% or greater. It also provides guidelines for clinical management.