The biological activities of Smilax china L. rhizome (SCR), hot water (SCRW) and 70% ethanol extract (SCRE) were analyzed. The total phenolic contents of SCRW and SCRE were 51.7 and 100.5 mg/g, respectively. The measured flavonoid content of SCRW (61.7 μg/g) was almost double that of SCRE (31.7 μg/g). SCRE (IC50=42.4 μg/mL) exhibited stronger antioxidant activity in the DPPH system than the positive control α-tocopherol (71.3 μg/mL) or butylated hydroxy anisole (53.8 μg/mL) did. SCRE (IC50=50.3 μg/mL) also showed stronger ABTS radical scavenging activity, as did α-tocopherol (67.1 μg/mL). The SOD-like activity and Tyrosinase inhibition activity of SCRW and SCRE showed almost the same pattern. The best SOD-like activity and tyrosinase inhibition activity were measured as 24.9% and 20.3% in SCRW at 1,000 μg/mL, respectively. The cytotoxic effects of the SCR extracts were analyzed via MTT assay on human cancer and normal cells. SCRW and SCRE did not show cytotoxicity up to the concentration of 1,000 μg/mL against the normal human cell line HEK293. Against human breast cancer cells (MCF-7), SCRW inhibited MCF-7 growth (by 27.6%) better than the anticancer drug cyclophosphamide (15.5%) at 1,000 μg/mL. SCRE (1,000 μg/mL) inhibited the growth of human lung cancer cells A549 (37.6%) and human stomach cancer cells AGS (53.6%) more effective than did SCRW (21.0% and 35.4%) or CPA (22.2% and 31.7%). These results suggest the potential use of SCRE and SCRW as an excellent antioxidant and antiproliferative substance, respectively.