Iron is an important mineral participating in many processes in our body. Its deficiency is still highly prevalent, taking place in many stages during lifetime, from infancy, adolescence, adulthood, elderly and pregnancy. Iron deficiency could be a risk factor for many pathologies, and be associated with relevant clinical, social and economic complications. Differential diagnosis should be performed with appropriate laboratory exams. Treatment with many iron forms and routes are effective, and should still be a concern to any physician.