Increased use of medicinal leeches (Hirudo medicinalis) for the treatment of venous congestion in flaps and replanted parts has coincided with reports of soft tissue infections following leech application. We cultured the gullets of 20 medicinal leeches to re-examine the antibiotic sensitivities of Aeromonas hydrophila, the leech enteric organism associated with reported infections. These isolates reflected reported resistance to penicillin and first generation cephalosporins as well as sensitivity to gentamicin, tetracycline and chloramphenicol. Additionally, the cultures were sensitive to cefamandol, cefoxitin and two third generation cephalosporins (cefoperazone and cefotaxime). These findings suggest that cefamandol, cefoxitin and some third generation cephalosporins may have a role as perioperative antibiotics in replantation and flap surgery. These antibiotics might provide prophylaxis against Aeromonas hydrophila infection when leech use is required.