A 48-year-old man presented with a vascular anomaly of the iris in the left eye. Slit-lamp microscopy revealed dilated and tortuous vessels of the iris between 12 and 4 o'clock. Fluorescein angiography confirmed a diagnosis of arteriovenous (AV) malformation of the iris. The vessel originated at the iris base, passed to the pupillary margin and returned to the base. Such AV-malformations of the iris are very rare, benign vascular anomalies that have to be distinguished from other, potentially malignant pathologies of the iris (e. g. tortuous vessels in iris melanoma).