This review provides a summary of the main objectives, significant design features, and major findings and achievements of the Collaborative Ocular Melanoma Study (COMS). It has been written by two ophthalmic oncologists who were not part of the COMS study group; therefore, it represents an extramural view of the trial to supplement summaries published by the COMS investigators. Because the randomized design of the COMS was unique, no attempt is made to make any comparison with the results of previous non-controlled studies.