The aims of the study were to find out the presence of Flavobacterium psychrophilum (F. psychrophilum) in commercial Rainbow trout farms in Middle and Eastern Black Sea regions and to determine the antibiotic susceptibility profiles of the isolated strains. For this purpose, total of 276 fish samples were collected from 18 different farms in these regions between January 2008 and July 2010. Bacterial isolation from samples was performed by conventional microbiological methods. In addition, Polymerase Chain Reaction (PCR) was used to confirm the identification and to detect F. psychrophilum in tissue samples. Nine of fish tissue samples were found to be positive for F psychrophilum by PCR. However, five F. psychrophilum strains were isolated from these samples and confirmed by PCR. The antibiotic resistance of the isolates against neomycine, oxyletracycline, enrofloxacin, amoxycillin, ampicillin, erythromycin, kanamycin, sulphamethoxazole+trimethoprim, cefoperazone and oxolinic acid were analyzed by Kirby Bauer agar disc diffusion test. The antibiotic susceptibility patterns of the isolates were variable. All the isolates were sensitive only to oxytetracyline (30 mu g) and enrofloxacine (5 mu g).