Intravascular lymphomatosis (IL) is a rare variant of non-Hodgkin's lymphoma with an unusual predilection for the central nervous system (CNS). Most cases are not diagnosed until postmortem because of variable clinical presentation and nonspecific laboratory findings. Neuroimaging findings vary widely and range from diffuse involvement of the deep white matter to infarct-like lesions. Cerebral magnetic resonance imaging (MRI) may show parenchymal and meningeal gadolinium enhancement. The authors describe brain MRI findings of linear, punctate, and patchy enhancement suggestive of CNS IL in two patients confirmed by brain biopsy/histologic studies. High index of clinical suspicion and careful interpretation of MRI (including gadolinium contrast studies) may contribute to premortem diagnosis and early intervention of this often-missed disease.