Intravascular lymphomatosis (IVL) is characterized by an intravascular proliferation of atypical mononuclear cells of haematopoietic origin occluding small blood vessels including venules, capillaries and small arteries, and can affect virtually any organ in the body. Clinically, the most common manifestations are involvement of the skin and central nervous system, although various organ involvement has been described. We report a patient who presented with fever and rash, and succumbed with acute neurological symptoms and systemic inflammatory response syndrome (SIRS) with no evidence of infection. The postmortem revealed disseminated involvement of virtually every organ with IVL, the malignant cells being of T-cell origin, which may secrete cytokines including tumour necrosis factor and interleukin-1, that are believed to be mediators in SIRS. In the absence of evidence of infection on microbiology and pathology, we postulate that the features of SIRS in this patient was due to the disseminated malignancy itself.