Abstract: C57BL/6N mice were administrated iv with Lewis lung carcinoma cells 1×105,and then ip interferon-α liposome (L-IFN-α)or interferon(IFN-α)for ten days.The lung metastasis foci and proliferation of splenocytes in mice were observed. The results showed that IFN-α inhibited the lung metastasis of Lewis lung carcinoma and increased proliferation of splenocytes in miceIp 1-20×104u·kg-1 of IFN-α for 10d, lung weight of mice decreased by 3.1-18. 8%;the numbers of metastasis foci decreased by 8.2-49.9%;and 3H TdR incorporation increased by 1.8-46.7%.After envelopment of IFN-α by liposome, its potency of anti-lung-metastasis of Lewis lung carcinoma and promoting proliferation of splenocytes increased 11 times as against unenveloped IFN-α. L-IFN-α had a more powerful effects of anti-metastasis and increasing proliferation of splenocytes in the mice administrated previously with cyclophosphamide than in the unadministrated mice.These results indicate that IFN-α liposome is a prospective preparation.