PLA-801D-AS was estblished from subcutaneous xenograft human gian cell carcinoma PLA-801D through serial intraperitoneal passages in nude mice,PLA-801D-AS could produce significantly higher incidence and number of spontaneous lung metastases than Did Subcutaneous PLA-801D.The subcutaneous PLA-801DL was derived from the metastatic lung nodules of ascitic PLA-801D-AS through serial passages in nude mice and It had increased lung-metastasizing potential than Did PLA-801D.The paper discussed the reasons for the enhanced metastatic capactity from metastatic heterogeneity of neoplasm,tumor cell-host interactions.