Background/Aims: Malnutrition has been encountered more frequently than expected and is associated with increased morbidity and mortality in hemodialysis (HD) patients. Until the last few years, only oral and enteral nutritional supplies have been used in the treatment of malnutrition in HD patients. However, intradialytic parenteral essential amino acid (EAA) nutrition has recently been introduced to treat these patients. The present study was conducted to compare both methods of EAA nutrition, oral and parenteral, in malnourished HD patients. Methods: Half of the 20 malnourished HD patients in this study received 0.9 g/kg/week of oral EAA (oral group), while the other half of the patients were treated with the same dose of parenteral EAA (parenteral group) for 4 months. However, at the very beginning of the study, 4 patients from the oral group were transferred to the parenteral group because of complaints such as nausea and vomiting. Therefore, this study was completed with 6 patients in the oral group and 14 patients in the parenteral group. Some biochemical parameters, including blood lymphocyte counts and anthropometric measurements as indicators of the nutritional status, were obtained from both of the groups in the pre- and posttreatment periods. Results: Following the treatment, there were no statistically significant differences between the groups with respect to anthropometric measurements. However, statistically significant increases were observed in serum albumin (p = 0.048) and creatinine (p = 0.006) levels and blood lymphocyte counts (p = 0.006) in the parenteral group, while there were statistically significant increases only in serum calcium (p = 0.028) levels and blood lymphocyte counts (p = 0.038) in the oral group following the treatment when compared to pretreatment values. Conclusion: These results show that parenteral EAA therapy is more comfortable and effective than oral EAA therapy in the treatment of malnourished HD patients.