Objective: Plantaricin CS and Snakin Z are two peptides that purified from innate immune systems of two different species. Because of their biological activities, the use of these peptides in a variety of medical applications is possible. For this purposes, investigation of hemocompatibility and cytotoxicity of peptides is necessary. Methods: Human red blood cells (RBCs) were treated with different concentration of peptide in two methods: radial diffusion assay and spectrophotometric assay. For in vivo assay, the mean of hematocrit, RBCs and White Blood Cells (WBCs) was assessed after treatment of 48 rats (24 rats for each peptide) with different concentrations of peptides (5,15,45,135 and 400µg/ml) for two weeks. Results: According to data, no significant changes were observed in the groups treated with Plantaricin CS in all concentration; but Snakin Z showed significant toxicity on all blood cells. This peptide decreases the RBC, WBC and Hematocrit as 4.1 RBC×1000000/µL, 12 WBC×1000/µL and 16% in concentration of 400 µg/ml, respectively. Conclusion: According to this study, both of peptides showed hemocompatibility in values that they have biological activities. So it's suggested that Snakin Z and Plantaricin CS may be suitable pharmaceutical agents.