The authors report five cases of abnormal iris vessels observed in patients, without evident local or systemic pathology. These vessels, are dilated channels. On iris fluorescein angiography their filling appeared earlier than in normal stromal vasculature and was synchronous with that of conjunctival vessels. No dye leakage was present. Two functional angiographic pictures are observable: 1) vessels with abnormal diameter and path, approximately following normal iris vessel arrangement (case 1 and 2); 2) atypical vessels with wide communicating shunt between artery and vein without collaterals (cases 3, 4 and 5). These vessels are very tortuous and do not show any abnormality. The authors suggest to consider these anomalous vessels as anatomic abnormalities comparable with the arterio-venous communications of the retina.