This study examined two gregarious Orthopteraspecies (Calliptamus barbarus and Oedaleus decorus) aspotential sources of chitin. The chitin content of the dryweight of C. barbarus was 20.5 ± 0.7%, and it was 16.5 ±0.7% for O. decorus. Furthermore, the yield of chitosan (70~ 75% deacetylation degree) from the grasshopper specieswas found to be 74 ~ 76%, which is close to the yield ofcommercial preparations obtained from the unused parts ofcrabs and shrimp. The chitin and chitosan obtained in thisway were analyzed using FTIR, TGA, XRD and SEMtechniques, and the antimicrobial properties of chitosansobtained from C. barbarus and O. decorus against pathogenicmicroorganisms of humans and fish were investigatedusing the disc diffusion and microdilution broth methods. The antimicrobial screening procedures indicated that thechitosan showed significant antimicrobial activity againstall of the tested pathogenic microorganisms. The MBC orMFC values were determined to be 0.16 ~ 2.50 mg/mL. The IC50 values for the chitins obtained from C. barbarusand O. decorus were 10.68 ± 0.27 and 10.91 ± 0.96 mg/mL,respectively, which were greater than the value forbutylated hydroxytoluene (BHT): 0.04 ± 0.01 mg/mL. These results suggest that these two species, which arecurrently considered to be pests because of over-breeding,are potentially alternative sources of chitin and chitosan,which are used in the food/feed industry for theirantimicrobial and antioxidant properties.