Introduction: Today, research in the field of antimicrobial peptides is active. Thus, the aim of this study is to purify and determine biochemical properties (especially antimicrobial effect) of new antimicrobial peptides from skin secretions of bufo kavirensis. Methods: This is a descriptive study. The skin secretions of bufo was purified by biochemical manners and antimicrobial effects was characterized by radial dffusion assay and minimal inhibitory concentration. The sequence of peptides was also determined by using MS/MS. Results: A novel antimicrobial peptide was obtained from skin secretions. This peptide is composed of 20 amino acids. This peptide does not present any similarity with the other antimicrobial peptides from the amphibians. Thus, it was named Maximin Bk. The peptide was subjected to antimicrobial activity assays. The Buforin–Kpeptide showed considerable antimicrobial activity against Gram positive and Gram negative bacteria (minimum inhibitory concentrations (MIC), 8.1 to 20.78 µg/ml) as well as fungi (MIC, 25.7 to 35.6 mg/ml). Moreover, this peptide showed higher antimicrobial activity against Gram-negative than against Gram-positive bacteria and fungi. Maximin Bk showed virtually low hemolytic activity, which, at a concentration of 100 μg/mL, induced 5% hemolysis. Thus, a very slight haemolytic activity was obtained against human erythrocytes. Conclusion: On the basis of the biological effects, Buforin–Kcan can be regarded as the potent agent for treatment of various microbial diseases.