The clinical and detailed angiographical findings taken during the follow-up of 182 patients with tumors of the iris and the ciliary body reported. On the basis of different angiographic staining patterns, these tumors were divided into three groups. Group I: Clinically, as a rule darkly pigmented, slightly or nonprominent tumors, which do not take up fluorescein at all, i.e. no staining of the tumor of its surroundings during the whole angiogram. 107 patients with such a tumor type did not show any clinical or angiographical changes during several years of follow-up. Those tumors which were excised (4) proved to be nevi. We therefore believe this fluorescein pattern indicates a benign lesion so that examination every 6 months suffice. Group II: These are usually less pigmented and only slightly prominent and have their own vascular network. On fluorescein angiography there is dye leakage within the tumor and into the surrounding iris stroma as well as into the aqueous humor. Of a total of 52 cases 9 were excised via iridectomy or iridocyclectomy. Of these 5 were shown to be benign nevi, 4 however were diagnosed as malignant melanomas. We therefore classify this fluorescein angiographical pattern as belonging to potentially malignant tumors, needing frequent controls, i.e. at 3-month intervals. Group III: Clinically these tumors are usually darkly pigmented, extremely prominent and mostly situated in the peripheral iris, originating here or spreading forward from the ciliary body. They are usually vascularized and show - if the melanin content is not too dense - early mottled staining in the vicinity of the tumor. They furthermore always have a marginal central borderline fluorescence as a typical sign, often accompanied by dye leakage from normal iris vessels, representing so-called 'tumor iritis'. 18 tumors of this type were excised via iridocyclectomy or enucleation and all were shown to be malignant melanomas of the iris or the ciliary body on histopathological examination. This fluorescence pattern group of tumors should always be regarded as definitely malignant, and therefore need prompt surgical excision.