Slow injection dynamic CT (SI-CT) was performed on 176 cases with gallbladder diseases. In this study we compared the enhancement degree of the focus on CT findings to its histological findings. Enhancement degree was classified into four grades. Most of foci classified into Grade I were confirmed to be necrosis histologically Grade II less epithelial component with more connective tissue, Grade II or IV more epithelial component with more connective tissue. The criteria of gallbladder cancer by SI-CT were determined by its form and enhancement degree as follows. 1. Polypoid type with Grade III, IV, 2. Mass forming type with any grade, 3. Locally thickened type with Grade II, 4. Locally thickened type with Grade III, IV, 5. Generally thickened type with Grade I, II. By this criteria, the diagnostic overall accuracy rate was 88%. SI-CT was considered to be useful examination in diagnosis for gallbladder diseases.