Mutations in the chromosome 1q-linked gene hemojuvelin (HJV) have recently been found to be a cause of juvenile haemochromatosis. We addressed the question of whether hemojuvelin mutations may influence the phenotype of patients with adult-onset haemochromatosis with or without mutations of the HFE gene. We sequenced the complete coding region of 133 subjects with iron overload. To screen a large number of patients, we also developed conditions for analysis by denaturing high-performance liquid chromatography (dHPLC). This diagnostic modality detects many mutations of the HJV gene. One patient with severe iron overload was found to be a compound heterozygote for HJV mutations, one of which had previously been identified in patients with juvenile haemochromatosis (G320V) and the other was novel (C321W). A number of other mutations were identified, but none were clearly associated with increases in the body iron burden. Notable among these was a DNA triplet insert, predicting an insertion of glycine, found in two African-American subjects, one with and one without iron storage disease.