Posterior spinal artery syndrome has a variable presentation and often poses a clinical challenge. We describe an acute posterior spinal artery syndrome in a man in his 60s with vascular risk factors, who presented with altered sensation in the left arm and left side of his torso but with normal tone, strength and deep tendon reflexes. MR imaging showed a left paracentral T2 hyperintense area affecting the posterior spinal cord at the level of C1. Diffusion-weighted MRI (DWI) showed high signal intensity in the same location. He was medically managed as having ischaemic stroke and made a good recovery. Three-month MRI follow-up showed a persisting T2 lesion but the DWI changes had resolved, consistent with the time course for infarction. Posterior spinal artery stroke has a variable presentation and is probably under-recognised clinically, requiring careful attention to MR imaging for its diagnosis.