Abstract: Objective The reason of false positive and false negative in primary gallbladder carcinoma diagnosed by B-ultrasonography was analysed,and how to improve the rate of accuracy of primary gallbladder carcinoma by B-ultrasonogrphy was discussed in this article. Methods The usual methods was used in gallbladder examination. Results 1 false positive and 4 false negative were made in 36 cases. Conclusion The major cause of misdiagnosis made by B-ultrasonogrphy could be caused by the follows:1) Deposited bile or condensed blood block in gallbladder forms irregular solid mass echoes which is easy to be misdiagnosed as gallbladder carcinoma.2)When the mount of stones cover the echoes of cancer,it could cause false negative.3)When the cancer occupys the whole gallbladder carity,it could be misdiagnosed as withering gallbladder cholecystitis.