Hematide is an investigational pegylated synthetic peptide that stimulates erythropoiesis in animal models and is being developed for the treatment of anemia associated with chronic renal failure and cancer. This study evaluated the safety and pharmacodynamics of single, intravenous doses (0.025, 0.05, and 0.1 mg/kg) of Hematide in 28 healthy male volunteers. All doses of Hematide were well tolerated, with safety profiles similar to those of placebo. Hematide showed a dose-dependent increase in reticulocytes. The 0.1-mg/kg dose was associated with a statistically significant increase in hemoglobin (Hgb) from baseline compared to the placebo group (13.6 +/- 3.9 g/L [1.36 +/- 0.39 g/dL] versus 3.9 +/- 3.8 g/L [0.39 +/- 0.38 g/dL]; P < .001) that was sustained for longer than 1 month. These results support phase 2 studies in patients with anemia associated with chronic kidney disease or cancer and suggest that Hematide administered as infrequently as once a month may result in a sustained elevation of Hgb levels. (Please note that Hematide is a proposed trade name; the compound does not yet have a nonproprietary name.).