地中海贫血（Thalassemia），又称海洋性贫血，简称地贫，是一种先天的血液疾病，和父母的遗传有关。1925年意大利首次报道了此病，目前该病已在全世界范围散布。患者的红血球较脆弱且生命周期短，带氧能力较不足。重度患者无法正常生活，不能有效地制造红血球，因而长期有溶血性贫血的现象；轻度患者则生活与常人无异，不需治疗亦无法治疗，HGB血红素总量可能介于正常范围，不会有缺铁性贫血的症状，因此难以察觉。此疾患可藉健康检查筛检出，基于优生学，建议于婚前筛检双方是否为带因者。地中海贫血是一种隐性基因遗传，患者红血球的体积较正常细胞小，中度以上患者有时因血红素含量低较苍白或呈靶型（target cells)。 由于此病流行于地中海、中东及东南亚一带地区，故被称为「地中海贫血」。

Thalassemia (British English: thalassaemia), also called Mediterranean anemia, is a form of inherited autosomal recessive blood disorder characterized by abnormal formation of hemoglobin. The abnormal hemoglobin formed results in improper oxygen transport and destruction of red blood cells. Thalassemia is caused by variant or missing genes that affect how the body makes hemoglobin, the protein in red blood cells that carries oxygen. People with thalassemia make less hemoglobin and have fewer circulating red blood cells than normal, which results in mild to severe microcytic anemia.