Progressive clinical deterioration over a period of weeks coupled with MRI evidence of infarction growth is quite uncommon. In this report, we describe a patient with an occluded left anterior cerebral artery (ACA) at the origin of the A2 segment. His symptoms attributable to a posteriorly located small infarction within the ACA territory slowly progressed during the following 8 weeks. A follow-up MRI revealed that the infarction had expanded to involve the whole region of the left ACA. Occasional patients like ours indicate that stroke is a dynamic disorder with an extremely variable clinical course and state of tissue injury. Copyright (C) 2002 S. Karger AG, Basel.