We attempted to analyse the computed tomographic (CT) characteristics of mass-forming pancreatitis. Thirty inflammatory masses were studied using the combined method of dynamic CT (Dy-CT) and high dose enhancement CT (HD-CT) with a thin-section scan. From the correlation between the CT enhancement effect and the histopathologic changes, injury of the glandular element and proliferation of fibrous tissue were more prominent in inflammatory masses showing a different enhancement effect from the surrounding pancreatic parenchyma. In addition to these changes, constriction of the intrapancreatic artery caused a poor enhancement effect on Dy-CT, whereas marked round cell infiltration with lymphoid follicle formation increased the enhancement effect on HD-CT. This combined CT method is valuable for the diagnosis of mass-forming pancreatitis and adequately reflects its histopathologic condition.