Background and Purpose It has been shown that etythrOpoietiti is neuroprotettive in animal models of neurodegenerative diseases including amyotrophic lateral sclerosis (ALS). The aim of this study was to determine the safety and feasibility Of repetitive hig1r4close recombinant human erythropoietin (rhEPO) therapy in ALS patients: Methods Two consecutive studies were conducted. We first recruited 26 subjects for an initial single-arm safety study. After a lead-in period of 3 Months to asseSS the diSease progression, rhEPO was infused intravenously (35,000 IU) once per month for 3 months, andd, the subjects were followed for an additional 3 months. The ALS Functional Rating Scale-Revised (ALSFRS-R) was used for clinical assessment After confirming the safety of rliEPO, 60 subjects were recruited for the second controlled study (rhEPO and control groups), winch involved a total of 6 infusions at a rate of 1/month. Results There were no serious adverse events in the first Study. 116 Mean tate of deCline in the ALSFRS-R score was lower during the treatment period than during the lead-in period (mean SD: 2.6 +/- 1.8 and 3.7 +/- 2.6, respectively; p=0,02). I-ToWeVer, -the rate of decline during the subsequent 3 months returned to that observed in the lead-in period. In-the seCOnd study, the Mean rate of decline in ALSFRS-R score was significantly lower in the rhEPO group than in the control group (during months 0-3, 1.8 +/- 1.7 vs. 3.1 +/- 2.3, p=0,03; duringnMotbs-4-6, 2.1 +/- 2.2 Vs. 3.5 +/- 2.3, p=0.02). Conclusions Intravenous high-dose rhEPQ is both safe and feasible for the treatment of ALS. Further investigation using different intervals' and doses should be considered,