The computed tomographic (CT) scans of 339 patients with recent nonhemorrhagic cerebral infarct and 155 patients with supratentorial tumors were reviewed to evaluate the appearance of cerebral edema. White matter pathway edema characterized the CT pattern in 106 (68%) of the 155 tumor cases. In these 106 cases, there were 143 tumors, with edema in the arcuate white matter (73%), the external capsule (33%), the internal capsule (12%) and the corpus callosum (14%). In contrast, only four of the 339 cases of infarct had edema in the white matter pathways. In addition, 260 (77%) of the infarct cases had edema in both gray and white matter and 98% had at least gray matter involvement, while only two of the tumor cases had any gray matter edema. White matter pathway involvement with respect to tumor site is useful in differentiating tumor and infarct edema.