Background: There is limited information available on zinc (Zn) or copper (Cu) deficiency during total enteral nutrition treatment. With more patients surviving long term while on enteral nutrition, these deficiencies may be more common.Methods: In our prospective study, 53 patients who received total enteral nutrition were admitted to our hospital for periodic replacement of gastrostomy catheters from March 1, 2013 to August 31, 2013. We measured the serum Zn and Cu levels on admission, and investigated the relationships of the levels on gender, the period after percutaneous endoscopic gastrostomy, the daily dosage of Zn or Cu, age, white blood cell count, hemoglobin (Hb) level, platelet count, and serum albumin (Alb) level.Results: The rate of low serum Zn level (43%) was significantly higher than that of low serum Cu level (9%) [Zn (23/53) vs. Cu (5/53), p = 0.0002]. None of the patients had high serum Zn level, whereas 26% of the patients had high serum Cu level [Zn (0/53) vs. Cu (14/53), p = 0.0002]. There was a significant positive correlation between serum Zn and Hb levels (r = 0.515, p = 0.00008), and a significant, weak positive correlation between serum Zn and Alb levels (r = 0.357, p = 0.009).Conclusions: Enteral nutrition may be an independent risk factor for Zn deficiency, and the Zn deficiency is associated with the decrease in the Hb level.