The Artemisia capillaris THUNB is a perennial herb that belongs to the family Compositae spp and probably the most common plant among the various herbal folk remedies being used in the treatment of abdominal pain, hepatitis, chronic liver disease, jaundice and coughing in Korea. Recently the biological and pharmacological actions of herb have been studied well such as antibacterial, antidiabetic and antitumor activities. This experiment was conducted to investigate antitumor and immunomodulatory effects of Artemisia capillaris extracts against Hepa-1c1c7 and Sarcoma 180 cancer cells in in vivo experimental tests. In in vivo experimental tests using 210 ICR mice, based on flow cytometry, CD3+, CD4+, CD8+ and TNF-${alpha}+$ splenocytes were significantly (p<0.05) reduced in the Hepa-1c1c7 and Sarcoma 180 inoculated vehicle controls, HP and SP, compared to those of the intact vehicle control on both the $28^{th}$ day and the $42^{nd}$ day, respectively. These decreases of CD3+, CD4+, CD8+ and TNF-${alpha}+$ cells induced by tumor inoculations were significantly (p<0.05) inhibited by mACH treatment regardless of the type of experiments and tumor cells inoculated. The results suggest that Artemisia capillaris methanol extracts have prominent antitumor effects on the cancer cell lines Hepa-1c1c7 and Sarcoma 180.