Obsessive compulsive disorder is characterised by recurrent, unwanted, distressing thoughts, images, impulses and associated behaviours which generally emerge in the 2nd or 3rd decades of life. Elderly onset cases are rare. A 71 year old patient was admitted to our hospital because of leftsided weakness. Neurological examination revealed left hemiparesis, mild dysphasia and anosognosia. Using cranial magnetic resonance, infarcts were found in the MCA territories, in the posterior portion of the middle temporal gyrus supplied by the cortical (inferior) branch and in the internal capsule, globus pallidus and putamen portions supplied by the lenticolostriate branch. An occlusion was also present in the right internal carotid artery (ICA). Fifteen days after presentation he developed an abnormal fear of urine contamination. He showered and handwashed excessively and exhibited insomnia and anxiety. The patient knew that his behaviour was ridiculous but could not prevent it. Formal neuropsychological testing found his simple attention to be mildly impared. His visuospatial function and construction abilities were also impaired. Obsessive compulsive disorder is usually an early onset disease. However this report seeks to draw attention to late-onset cases such as this, which are due to a cerebrovascular disorder.