Hookworms are among the most widespread of human parasites and occur all over the tropics and subtropics. They are bloodsucking roundworms that inhabit the duodenum and jejunum. Usually the infection is mild (hookworm carrier state), but sometimes the infection is heavy and results in anaemia and/or hypoproteinemia (hookworm disease). Hookworms are occasionally imported to Norway by immigrants. This paper describes two cases of severe and life-threatening hookworm disease treated in our hospital. The first patient was a Pakistani woman born in 1929 who on admission was hypovolemic with severe hypochromic anaemia (haemoglobin 3.6 g/100 ml). The second patient was a Bolivian refugee born in 1946 with a similar clinical picture (haemoglobin 3.3 g/100 ml). Both patients were treated with blood transfusions followed by mebendazol and iron substitution. The article also reviews the current literature on the epidemiology, pathogenesis and therapy of hookworm infection.