Copper is an essential cofactor in many enzymatic reactions vital to the normal function of the hematologic, vascular, skeletal, antioxidant, and neurologic systems. Copper deficiency in the United States is believed to be relatively rare but has been described in the setting of zinc supplementation, myelodysplastic syndrome, use of parenteral nutrition and chronic tube feeding, and in various malabsorptive syndromes, including following gastrectomy and gastric bypass surgery. Features of copper deficiency include hematologic abnormalities (anemia, neutropenia, and leukopenia) and myeloneuropathy; the latter is a rarer and often unrecognized complication of copper deficiency. We here describe two patients who presented with severe gait abnormalities and anemia combined with neutropenia several years after roux-en-Y gastric bypass (RYGB) surgery for obesity who were found to be severely copper deficient. Intravenous copper repletion resulted in the rapid correction of hematologic indices; combined intravenous and oral copper supplementation and eventual oral copper supplements alone normalized serum copper levels in each patient, but resulted in only partial resolution of the neurologic deficits. This report serves to alert physicians of the association between RYGB procedures and subsequent copper deficiency in order to avoid diagnostic delays and to improve treatment outcomes.