Background and Objectives: Tetanus is a deadly zoonotic infectious disease. For nearly a century, tetanus vaccine has been produced and used. This study was carried out with the aim of preparation and evaluation of immunogenicity of chitosan nanoparticles containing tetanotoxin in comparison with Freund's adjuvant in mouse model for improvement of tetanus vaccine after subcutaneous onjection. Methods: In this experimental study, chitosan nanoparticles synthesis containing tetanus toxoid was performed using ionic gelation method. The morphology of nanoparticles was investigated using SEM and AFM, then, the nanoparticles were subcutaneously injected into mice and two weeks after the end of injection, blood was taken. Antibody titer was measured by indirect ELISA. Data were analyzed using one-way one-way ANOVA and Tukey test at significance level of p