Beta thalassemia is an inherited blood disease of abnormal hemoglobin production in which both beta-globin subunit components of normal hemoglobin are absent.

The estimated incidence rates of beta thalassemia vary by population and it is more commonly found in areas around the Mediterranean Sea; in Italian, Sicilian, and Greek populations, the incidence is approximately 10%; in African populations, it is approximately 1.5%; in the African American population, the incidence is approximately 1.5%; and in Southeastern Asian populations, it is approximately 5%.

The manufacture of beta-globin molecules has been traced to chromosome 11. More than 200 mutations of the beta-globin genes on chromosome 11 that can result in thalassemia have been documented. The result of the particular mutation is either the absence of the beta-globin, called beta(0)thalassemia, or diminished beta-globin, called beta(+) thalassemia.