Abstract: OBJECTIVE To investigate proliferative activities for peritoneal macrophages and splenic lymphocytes in mice and anti-oxidative potency in vitro of n-butanol extract of Radix isatidis. METHODS 12 components were extracted and separated from Radix isatidis by n-butanol. Each component of total n-butanol extracts was detected and analyzed by HPLC. The proliferative activities of each component for peritoneal macrophages and splenic lymphocytes were detected by MTT assay. Anti-oxidative activities were evaluated by DPPH and ABTS radical scavenging and FRAP method. RESULTS No. 2， 6， 7 and 11 components showed the most potent proliferation on immune cells， with the highest proliferation index>3. No. 2 and 6 components displayed the strongest antioxidant activities， with IC₅₀ values on DPPH of 0.391， 0.164 mg/mL， ABTS of 0.164， 0.338 mg/mL and Fe³⁺ reducibility values of 1.441， 0.812 mmol/g equivalent weight of FeSO₄， respectively. CONCLUSION The n-butanol extract of Radix isatidis exhibit promoting proliferation for peritoneal macrophages and splenic lymphocytes and pontent antioxidant activities. Further investigation of the chemical structure will help to clarify the material basis for Radix isatidis antiviral effects.