A 17 year-old man with a one-year history of Crohn's disease presented with superior sagittal sinus thrombosis in spite of an apparent remission of the inflammatory bowel disease. Under treatment, the neurological disorders rapidly improved. Hematological studies showed mild thrombocytosis, spontaneous platelet aggregation, and an increase of the fibrinogen level, plasmatic viscosity and red blood cells aggregability. Mild hypofibrinolysis and antiphospholipid antibodies were also noted. Nine fully documented cases of cerebral venous thrombosis associated with an inflammatory bowel disease are reviewed. The possible prothrombotic role of thrombocytosis and other hematological disorders is discussed.