From 1965 to 1981, 43 cases of metastatic tumors were examined without localizing the initial primary site. All the cases were subjected to intensive studies to detect the primary, and most cases received multidisciplinary treatment. In 19 cases it was not possible to discover the primary tumor, and 6 of them are alive 2 to 9 years after the diagnosis. In 24 cases the primary tumor was subsequently located, but 23 of them died 1 to 5 years after diagnosis of the primary. One case is alive after 9 years. The actual point of view vis-a-vis this pathology and the rationale and active plan to obtain worthwhile results are discussed.
