Uveal melanomas are slow growing tumors that may infiltrate out of the eye, mainly following ciliary vessels or nerves, or invade blood vessels, but only rarely do they produce metastatic disease before discovery and treatment. There are, however, large gaps in our knowledge of the frequency and rate of growth of small tumors to those of moderate or large size. We have estimated the mortality from untreated uveal melanomas to be 1% per year or less. Almost all information concerning prognostic factors has been gained from studies based on cases treated by enucleation. The same information is not necessarily applicable to untreated tumors. A study of deaths from metastatic uveal melanomas reveals a striking relationship to enucleation, regardless of whether one deals with cases in which the eye had been symptomatic for a long or short time. Following a low preoperative mortality of 1% or less, the annual mortality rises to about 4% during the first year and then peaks at 8 to 12% during the second year, tapering off during the next three to five years to return to a remarkably constant level of 1 to 2% thereafter. We postulated that this relationship of peak mortality to enucleation is attributable mainly to an often overwhelming dissemination of tumor cells taking place during surgery or to a lowering of the host's immunologic defense mechanisms as a consequence of the operation, or both. We urge the pooling of all available information gained from clinical studies made on untreated tumors and recommend prospective studies of a variety of other methods of treating uveal melanomas in addition to the standard enucleation.