The cases of transvitreal retino-choroidal (TVRC) biopsy from 1987 to 1994 were assembled in order to examine the efficiency, complications and risks to patients. Of 92 biopsies 91 had sufficient material for diagnosis. Eighty (87%) contained malignant tissue, whereas 10 cases were negative and two unsuccessful. Tumours of appropriate size were treated by brachytherapy. Twenty-three large tumours were enucleated primarily. Eight irradiated eyes had to be removed. In 31 cases, therefore, it was possible to examine the whole tumour for changes caused by the biopsy and to compare the typing of the biopsy with that of the whole tumour. In the irradiated eyes histologically viable tumour cells remained mostly in the inner part of the tumour. Scleral necrosis was not found. The technique used appears to be safe. Histological verification is highly recommended before any conservative therapy, inter alia to obtain true statistics of therapeutic results.