Introduction: Obesity is an internationally health crisis. The bariatric surgery offers treatment to reduce body weight, induce remission of obesity-related diseases and improve quality of life. Nutritional deficiencies may have been installed even before surgery, and preoperative anemia is an independent risk factor. Thus, the present study aims to evaluate iron deficiency in obese candidates for bariatric surgery, attending a nutrition ambulatory of a university hospital in Recife/Brazil. Methods: Cross-sectional, descriptive study. The patients were evaluated according to sex, age, weight, body mass index (BMI), iron and ferritin levels. Iron deficiency was classified by levels <50 Ug/dl and <65 Ug/dl for women and men, respectively. The ferritin levels classified as deficient were those below 15 ng/ml for both sexes. Data collection was performed from May 2017 to June 2018, using data from nutrition setting’s monitoring forms. Data were tabulated and analyzed using Microsoft Excel software version 10. Results: 75 patients were included, with prevalence of women (85.3%), mean BMI of 47.99 ± 7.56 kg/m2. The means of serum iron (n = 70) and ferritin (n = 60) were 76.33 ± 37.06 Ug/dl and 160.82 ± 159.43 ng/ml, respectively. There was a high prevalence of serum iron deficiency (62.9%); however, ferritin was deficient in only 1.7% of the study population. Conclusion: This study observed an important presence of iron deficiency in the group of obese patients evaluated, with the greatest sensitivity being detected by means of serum iron. The biochemical evaluation of the patient who will be submitted to the bariatric procedure is important, in order to avoid health issues and postoperative complications, thus helping in their recovery.