Alpha-thalassemia is a common hereditary anemia due to decreased or absent synthesis of alpha-globin chains. The most common causes of alpha-thalassemia are deletions that remove one or both functional alpha-globin genes, with a small proportion of cases involving nondeletional mutations of the alpha2- or alpha1-globin genes. Herein, we describe a single-tube multiplex amplification refractory mutation system (ARMS) assay for rapid detection of six of the most common and severe nondeletional alpha-thalassemia mutations. These alleles are found predominantly among southeast Asian populations, and are associated with the most severe forms of hemoglobin (Hb) H disease or Hb H hydrops fetalis.