Acute inflammation of the umbilical cord, acute funisitis, is a sign of fetal inflammatory response, and the clinicopathological need for its identification is increasing. This study was conducted in order to describe the topographic distribution of acute funisitis, and thereby to provide more information on the intrinsic nature of acute funisitis and find a better way of pathologically examining the umbilical cord. A total of 10 umbilical cords affected by acute funisitis were histopathologically examined throughout their entire lengths at 1 mm intervals. Pathological examination was done to characterize the extent of the funisitis, the involvement of the vein (phlebitis) or of one or both arteries (arteritis), and the presence of inflammation in Wharton's jelly. Umbilical cord plasma interleukin (IL)-6 was measured by specific immunoassay to assess whether or not the severity of acute funisitis correlates with fetal cytokine response. It would appear that the inflammatory reaction begins as a discrete, multifocal process which eventually becomes contiguous as the inflammatory reaction proceeds. Umbilical cord plasma IL-6 concentrations tended to correlate with the extent of umbilical cord inflammation. The initial phase of acute funisitis involves discrete and multiple foci along the length of the umbilical cord. Moreover, the extent of acute funisitis reflects the severity of systemic fetal cytokine response. Therefore, adequate sampling using multiple sections would facilitate the identification of acute funisitis. We propose a standard sampling procedure taking one section from each third of the umbilical cord.