A method, namely macrophage biospecific extraction and high performance liquid chromatography for screening potential immunological active components in Cordyceps sinensis, a well-known traditional Chinese medicine, was developed. Two components, which could interact with macrophage, in aqueous extract of C. sinensis (WECS) were found by comparing the HPLC chromatograms of WECS before and after interacted with macrophage. The two compounds were identified as guanosine and adenosine. Their effects on mice macrophage were also investigated in vitro. The results showed that adenosine and guanosine could attenuate NO (p < 0.01) but augment interleukin-lβ (IL-1β) (p < 0.05) release of macrophage during the tested concentrations. In addition, guanosine (0.10 μmol/ml) also increased alpha-tumor necrosis factor (TNF-α) release of macrophage. The data suggest that macrophage biospecific extraction and HPLC is a useful method to screen immunological active components from Chinese medicines. © 2007 Elsevier B.V. All rights reserved.