During a five-year period uveal melanoma was diagnosed in 11 patients in the 6 months after lens-implant surgery. Pre-operatively all but one of the patients had bilateral senile cataract. The tumours were remarkably large and localised in the periphery rather than in the posterior pole (mean maximum tumour diameter 12.5 mm); they were therefore present at the time of surgery. An adequate pre-operative diagnostic ultrasound examination had not been performed in any of the patients. A plea is therefore made for the performance of an echographic examination in all eyes with opaque media in order to exclude solid lesions or other pathology in the vitreous cavity.