Stenotrophomonas maltophilia which causes nosocomial infections is an opportunistic pathogen commonly found in the environment. The bacterium is known to have intrinsic resistance to many antimicrobial agents due to its beta-lactamases, aminoglycozid acetyl-transferases, enzymes inactivating erythromycin and genes that code efflux pumps. During the antimicrobial chemotherapy, many problems arise due to this resistance. The aim of this study was to determine the antimicrobial susceptibilities of 36 clinical isolates of S. maltophilia collected from 31 patients in Akdeniz University Hospital Central Laboratory Microbiology Department, during August-October 2003 period. The strains were tested for susceptibility to trimethoprim-sulfamethoxazole (TMP/SMX), ticarcillin-clavulanate (TIM) and ciprofloxacin (C) with E-test. All of 36 S. maltophilia strains were susceptible to TMP/SMX, 24 of 36 (%66) were susceptible to TIM and 26 (%72) were susceptible to C. The result of the study showed that the most effective antimicrobial agent against S. maltophilia strains isolated from clinical specimens was TMP/SMX.