An anti-tumor alkaloid, Camptothecin, has been isolated from the stem of Camptotheca acuminata and the structures of this compound and its analogues were reported by Wall and his associates. In the present paper, we report the isolation procedure and identification of Camptothecin from the cells of Camptotheca acuminata suspension cultures. A cell line derived from C. acuminata was incubated in Murashige and Skoogs medium containing 0.1mg/liter 2,4-dichlorophenoxyacetic acid, 3mg/liter kinetin and 23.5mg/liter L-tryptophan under specific conditions. Isolation and purification procedures included extraction from lyophilized cells with hot ethyl alcohol, continuous extraction with chloroform, column chromatography and preparative thin-layer chromatography on Silica Gel G. The existence of Camptothecin was confirmed by thin-layer chromatography with specific solvent systems and fluorometric method. 1.98mg of purified material was obtained, corresponding to 2.54×10⁻⁴% of dry cell weight. Identification via UV spectrum (absorption peaks at 219, 253, 290 and 350~370nm, consistent with Wall et al.), mass spectrum (parent peaks at m/e=348 corresponding to Camptothecin, fragmentations matching authentic sample) and TLC Rf-values showed the isolated material is Camptothecin.