Cyclotides are mini-proteins that are synthesized via the ribosomal pathway. They have a variety of biological activities such as antimicrobial, antitumour, anti-HIV activities. Because of their various bioactivities and unique stability, they are suitable candidate in drug design applications. The main aim of this study was to determine new antimicrobial agents, which can be used instead of chemical antibiotics. For this reason, we compared the antimicrobial effects of semipurified cyclotides against human and plant pathogenic bacteria.