Abstract: A thirteen years old girl from Shandong province,China,suffered from a rare deep tissue progressive gangrene of upper extremities,for which the etioloical agent was un-known.The gangrene was so severe that it could not be limited by long term antibiotics treatment couplig with incision,debridement and radical amputation.The case had been concerned by the society ans news medium.With samples taken from deep tissue of the patient,eight species of bacteria were isolated,named as Staphylococcus aureus,Streptococcus acidominimus,Actinomyces odontolyticus,Eubacterium lentum,Peptostreptococcus productus.Pseudomonas aeruginosa and two unidentifiable organisms,which did not match any species of the proven list of bacteria-called Y6-9 and YP.By using western blot method,it was proved that patient's serum contained specific antibodies against all of the isolated bacterial species mentioned except A.odontolytics.Antibiotics susceptibility data showed that Pseudomonas aeruginosa strain was resistent to 37 of the 59 antibiotics tested.Only 4 of the 59 were effectively against all of the 8 bactenal species,named as cefoperazone,piperacillin,tobramycin and tienemimipenem+cilaastain sodium.The patient didn't respond clinically to cefoperaxone and piperacillin.Tobramycin was not used for treatment.When tienem was used,the infection was controlled.Our data suggested that it was a multibacterial synergetic gangrene.