Christmas Island is a remote Australian territory 2,400 km north of Perth. Health care is administered from Perth. The population is predominantly Chinese, with some Malay, Indian and European. As hemoglobinopathies are known to be common amongst these ethnic groups, a study was performed to determine their prevalence and significance in the Christmas Island population. Three-hundred and sixty-four individuals (adults and children) were tested. All subjects were assessed by full blood count, α-globin multiplex polymerase chain reaction (PCR) and PCR testing for Hb Constant Spring [α142, Term→Gln, AA→CAA (α2)]. Microcytic patients (MCV <80 fL) were further investigated by high performance liquid chromatography (HPLC) and serum ferritin was determined. Where present, β-thalassemia (thal) mutations were characterised by PCR. Thirty-four subjects (9.3%) were microcytic and of these five were iron deficient. The remainder were heterozygous for a hemoglobinopathy, giving a 9.1% incidence of hemoglobinopathies in Christmas Islanders. α-Thalassemia was identified in 23 subjects, seven of whom were heterozygous for α-3.7; the remaining 16 were heterozygous for the - -SEA deletion. One case of heterozygous δβ-thal and one case of heterozygous Hb E [β26(B8)Glu→Lys] was detected. Of the eight subjects heterozygous for β-thal, at least five mutations are represented, indicating a diverse and heterogeneous origin for this population.