This experiment was designed to study the change of cytotoxic and antitumor effects according to the prebrewed method of Semen Tiglii and Rhizoma Coptidis. The cytotoxic and antitumor effects were evaluated on human cell lines(A 549, Caki-1, LL2, Sarcoma 180, NIH/3T3) after exposure to prebrewed Semen Tiglii and Rhizoma Coptidis water extract 0.1, 0.2, 0.4, 0.8, 1.6 mg/ml using in MTT assay, LDH, colony forming efficency and SRB assay which were regarded as a valuable method for cytotoxic and antitumor effects of unknown compound on tumor cell lines. The results obtained in this studies were as follows. 1. The cytotoxicity from the result of MTT assay was low slightly in the ST II(炒巴豆霜), high in the ST III(醋炒巴豆). The cytotoxicity of ST I + RC(生巴豆霜加黃連) was similar to that of STI(生巴豆霜). 2. The cytotoxicity from the result of LDH was low slightly in the ST Ⅱ (炒巴豆霜), high in the ST III(醋炒巴豆). The cytotoxicity of ST I + RC(生巴豆霜加黃連) was similar to that of ST I(生巴豆霜). 3. The antitumor affect on A 549 tumor cell from the result of colony forming efficiency was low slightly in the ST II (炒巴豆霜) and ST I + RC(生巴豆霜加黃連). 4. The antitumor effect on Caki-1 tumor cell from the result of SRB assay was low slightly in the ST II (炒巴豆霜). 5. Median survival time and Increased life span increased slightly in the ST I RC(生巴豆霜加黃連) and ST II (炒巴豆霜). 6. The inhibitory effect on the growth of Sarcoma 180 and Lewis lung carcinoma tumor cell increased slightly in the ST I + RC(生巴豆霜加黃連) and ST II (炒巴豆霜).