Ceragenins are novel promising agents for the treatment of infections caused by multi-drug resistant microorganisms. Since colistin resistance has become a worldwide problem, the need for new treatment agents has been increasing steadily. Therefore, this study aimed to investigate in vitro antimicrobial activities of ceragenins (Cationic Steroid Antibiotics) (CSA-8, CSA-13, CSA-142 and CSA-192) against multidrug resistant Gram negative isolates from Turkey. Experiments were performed by using broth microdilution method against Klebsiella pneumoniae, Morganella morganii, Pseudomonas aeruginosa and Stenotrophomonas maltophilia isolates. All microorganisms except for three isolates were identified as multidrug resistant. Among tested ceragenins, CSA-13 showed the best results (MIC: 8-64 mu g/ml). Nevertheless, the antimicrobial activity of CSA-8 was not significant. In conclusion, ceragenins appear to be a good candidate as antimicrobial therapy in the presence of multidrug (including colistin) resistant microorganisms.