In major elective surgery, patient may be exposed to the effects of pre-operative anemia, blood loss and red cell transfusion, all of which may adversely influence post-operative rates of morbidity, mortality and readmission, and length of hospital stay. Preoperative anemia is prevalent among patients scheduled for major surgery (30-40%), while postoperative anemia is even more frequent (up to 80-90%). However, preoperative anemia is usually regarded as no more than a surrogated marker of patient's physical status, and it is not always adequately addressed before surgery, whereas red blood cell transfusion is the usual default treatment for postoperative anemia. Absolute iron deficiency and iron sequestration are the leading causes of preoperative anemia, whereas surgery-associated blood loss and inflammation may induce and/or maintain postoperative anemia. Hematinic deficiencies without anemia may hamper pre-operative hemoglobin optimization and/or recovery from postoperative anemia. As modifiable risk factors, preoperative anemia and hematinic deficiencies should be detected, classified and treated prior to any major surgery. For elective non-cancer procedures, this may entail to postpone surgery until anemia improvement or resolution.