Comparison of the radioisotopes of iodine and gold was made by a controlled trial treating lymph node metastases from VX2 tumor in the rabbit by the endolymphatic route. Control animals received tumor inoculation only, and 2 further groups received either 4mCi 1311 radioiodine in ultrafluid lipiodol or 8mCi Ado* colloidal radiogold. The primary tumor was excised a t 8 to 10 days after inoculation in all animals. Pelvic node weight was the main factor on which the trial was assessed. A significant difference in node weight was found between the treated a n d control groups, b u t there was no significant difference between the treated groups. No significant increased incidence of lung metastases was found in animals receiving endolymphatic infusions. NDOLYMPHATIC RADIOTHERAPY HAS BEEN EX-E tensively used in the surgical management of malignant melanoma and has also been employed in the therapy of lymph node metastases from other tumors. Radioactive iodine 1311 triolein in ultrafluid lipiodol has been investigated in great detail by Edwards et al. Other authors, including Chiappa et al. and Chiappa and Galli, have studied 1311 labelled ethiodol both in animal research and in clinical practice. Radioactive colloidal gold Ad98 has also been successfully employed clinically in this department since 1958.8-11 Seitzman et al. experimented with a combination of gold AulsB