In most cases, the histopathological examination of pulmonary metastases will lead to vital clues indicating the primary tumor even after years of disease-free intervals. When evaluating 344 metastases of 100 patients, correlation to the known primary tumor was possible in 98% of the cases. Important additional information may be gained by regression grading of metastases, for example after chemotherapy. In 28 metastases of 4 patients suffering from primary tumors of the testicle, no vital tumor tissue could be demonstrated. The age peak of patients with surgically removed pulmonary metastases was between 40 and 50 years, varying widely, however, depending on the primary lesion. The size of the resected metastases was between 1 and 100 mm, with a peak of 6-10 mm. The examination of early metastases enhanced our knowledge concerning the different phases of metastatic spread such as embolization, implantation, metastatic growth with neoangiogenesis, spontaneous or therapeutically induced tumor regression and local reactions of the pulmonary tissue. The characterization of tumor tissue using, among others, immunohistochemical techniques will lead to clinical and therapeutic consequences.