Fluorescein iridoangiography of 33 eyes with benign tumours and 22 eyes with malignant tumours is discussed. In cases of leiomyoma the tumour vessels have a distinct pattern, and fluorescence of the tumour tissue is mottled and short-lived. Malignant tumours are characterised by distortion of their vessels. Simultaneously the patches of fluorescence appear in the tissue of the tumour and lead to a diffuse confluence. Changes in the architecture of the vessels of the iris near the tumour and absence of fluorescence at the pupil margin indicate growth of the neoplasm.