Ancylostoma duodenale and Necator americanus are extremely common species of soil-transmitted helminth which flourish where poverty and malnutrition prevail. Hookworms contribute significantly to iron-deficiency anaemia, which remains one of the world's major nutritional problems, through the feeding activities of intestinal stages leading to chronic blood loss into the gut. In this article, a mathematical model is proposed to explain how human iron metabolism may respond to hookworm infection of varying intensity. The model draws attention to the importance of the regulation of stored iron levels in the process. The results from the model are presented for the effects of hookworm infection on the iron metabolism of a healthy adult male. Calculations are also presented in which the effects of hookworms on the iron metabolism of a non-pregnant woman are compared with those of a pregnant woman. Use of the model may help develop a better understanding of the pathology of hookworm disease.