Although the ultrasonography has been regarded as a main procedure in the diagnosis of gallbladder diseases, no many papers concerning the ultrasonographic findings of gallbladder empyema appeared in the literature. Twenty-four cases of surgically proven gallbladder empyema were studied by ultrasonography in our hospital during last 15 months. The results were as follows : 1. The size of gallbladder was enlarged in 18 cases. 2. The thickness of gallbladder wall was diminished in all cases. 3. The echogenicity of gallbladder wall was diminished in all cases. The inner margin of gallbladder wall was also ill-defined in all cases. These findings are considered to be important in the diagnosis of gallbladder empyema. 4. The internal echogenicity of gallbladder (diffuse or localized) was positive in 16 cases and negative in the remaineders. The echogenility was thought to be proportional to the amount of pus in gallbladder. 5. The 7 cases presented periocholecystic sonolucent area had perforation of gallbladder and pericholecystic abscess. 6. Gallstone was found in 17 cases.