Graft-vs-host-disease (GVHD) can complicate allogeneic bone marrow transplantation (BMT) and usually targets host skin, liver and gut. Reports of central nervous system (CNS) GVHD are very rare and diagnosis is challenging due to the range of potential neurological complications following BMT. We report a 20-year-old male, on cyclosporin following allogeneic BMT 18 months previously for acute myeloid leukaemia (AML), who presented with a right hemiparesis. He previously had cutaneous and hepatic GVHD which stabilised with immunotherapy manipulation. MRI brain demonstrated acute infarction in the left basal ganglia and left periventricular white matter. Magnetic resonance angiography (MRA) demonstrated irregularity of middle and anterior cerebral arteries. Cerebrospinal fluid (CSF) analysis did not reveal evidence of opportunistic infection. CSF cytology and vasculitic serology were negative. Repeat bone marrow aspiration revealed that his haematological malignancy had changed morphology. Despite maximising his immunotherapy, sequential brain imaging and blood films showed disease progression. His cutaneous and hepatic GVHD recurred and biopsies confirmed inflammatory vascular changes. The progressive course, sequential imaging findings and lack of evidence for alternative diagnoses is compatible with CNS-GVHD. It is important to consider CNS-GVHD in BMT patients presenting with neurological symptoms as it has significant treatment and prognostic implications.