BACKGROUND: The major causive factors of gallbladder carcinoma are very complex. Cholecystitis with gallstone was reported one of the most important factors. Many re- search revealed that cholecystitis or gallstone can give rise to epithelial hyperplasia of gallbladder mucusa or cancera- tion secondarily. In this study, 46 patients were detected in order to find the relationship between infection of different bacteria and formation of gallbladder carcinoma. METHODS: Using the common gene primer of bacteria 16S ribosomal RNA (rRNA), we detected bacterial gene fragments of gallbladder carcinoma tissues in 46 patients by polymerase chain reaction (PCR). Relative bile was also detected by PCR in 18 patients who underwent operations, including U-tube drainage (1), right or left biliary tube drainage (4), radical cholecystectomy (9), and cholecystor- rhaphy (4). The tissue fragments of gallbladder carcinoma from the remaining 28 patients were paraffin slices. RESULTS: The positive rate of bacterial DNA in gallblad- der carcinoma tissue was 78.3% (36/46). The sequence of 16S ribosomal RNA gene fragments amplified by PCR was approximately 371 base pairs (bp). Multiple kinds of stan- dard bacterial gene fragments obtained from 36 patients in- cluded Colibacillus, B.fragilis, Klebsiella, C. perfringens and Clostridium, with a positive rate of 78.3% (36/46). Among the 36 patients, 14 patients with gallbladder carcinoma re- ceived operation and their relative bile at operation was de- tected bacterial gene fragments with a positive rate of 77.8% (14/18). This result was close to that in gallbladder carcinoma tissues. CONCLUSIONS: Our results suggested that there might be a relationship between occurrence of gallbladder carcinoma and infection of different kinds of bacteria, especially anae- robic bacteria—C.perfringers. This reminds us that the gall- bladder mucosa stimulated by anaerobic and aerobic bacte- ria might be the principal cause for the development of car- cinoma. BACKGROUND: The major causive factors of gallbladder carcinoma are very complex. Many re- search revealed that cholecystitis or gallstone can give rise to epithelial hyperplasia of gallbladder mucusa or cancelation- secondarily. In this study, 46 patients were detected in order to find the relationship between infection of different bacteria and formation of gallbladder carcinoma. METHODS: Using the common gene primer of bacteria 16S ribosomal RNA (rRNA), we detected bacterial gene fragments of gallbladder carcinoma tissues in 46 patients by polymerase chain reaction (PCR). Relative bile was also detected by PCR in 18 patients who underwent operations, including U-tube drainage (1), right or left biliary tube drainage (4), radical cholecystectomy cholecystor-rhaphy (4). The tissue fragments of gallbladder carcinoma from the remaining 28 patients were paraffin slices. RESULTS: The positive rate of ba The sequence of 16S ribosomal RNA gene fragments amplified by PCR was approximately 371 base pairs (bp). Multiple kinds of stan- dard bacterial gene fragments obtained from 36 patients In the impacted Colibacillus, B. fragilis and Klebsiella, C. perfringens and Clostridium, with a positive rate of 78.3% (36/46). Among the 36 patients, 14 patients with gallbladder carcinoma re- ceived operation and their relative bile at operation was de- tected bacterial gene fragments with a positive rate of 77.8% (14/18). This result was close to that in gallbladder carcinoma tissues. CONCLUSIONS: Our results suggested that there might be a relationship between occurrence of gallbladder carcinoma and infection of different kinds of bacteria, especially anae-robic bacteria-C. perfringers. This reminds us that the gall- bladder mucosa stimulated by anaerobic and aerobic bacte-ria might be the principal cause for the development of car-cinoma.