Bariatric surgery has become a recognized tool to reduce weight and resolve or improve comorbid conditions associated with obesity. Patients with obesity are at risk for nutritional deficiencies because of poor-quality diets and the chronic inflammatory state of obesity. Iron deficiency is common in these patients, with incidence rates as high as 21.5% preoperatively and 49% postoperatively. Iron deficiency is often overlooked and not treated, leading to increased complications. This article reviews the risk factors for developing iron-deficiency anemia, diagnosis, and treatment considerations for oral versus IV iron replacement for patients undergoing bariatric surgery.