Introduction. Few data are available on vitamin A deficiency in the gastric bypass population. Methods. We performed a retrospective chart review of gastric bypass patients (n=69, 74% female). The relationship between serum vitamin A concentration and markers of protein metabolism at 6-weeks and 1-year post-operative were assessed. Results. The average weight loss at 6-weeks and 1-year following surgery was 20.1±9.1 kg and 44.1±17.1 kg, respectively. At 6 weeks and 1 year after surgery, 35% and 18% of patients were vitamin A deficient, (