OBJECTIVE:To study the antitumor activity of Anthopleura xanthogrammica crude extract on human lung cancer SPC-A1 cells in vitro. METHODS:A. xanthogrammica crude extract obtained by the methods of repeated freezing and thawing,ac-etone precipitation. After treated with crude extract 0(blank control),0.625,1.25 and 2.5 mg/ml for 24,48 and 72 h,the activity of SPC-A1 cells were measured by MTT assay. The growth inhibition rate and IC50 were also calculated. 24 h later,the morphologi-cal changes of SPC-A1 cells were observed by HE staining and AO/EB fluorescence staining. RESULTS:MTT assay showed that A. xanthogrammica crude extract has significant inhibitory effect on the proliferation of human lung cancer SPC-A1 cells;with the increasing of the concentration and the extension of the time,the inhibitory rate was increased. Its 24 h,48 h ,72 h IC50 were 1.81,1.32 and 1.18 mg/ml. HE staining and AO/EB staining appeared obvious morphological changes of apoptosis that cell mor-phology narrowed,vacuoles arose in the cytoplasm,karyopyknosis and part of nuclear disappearance occurred. CONCLUSIONS:A. xanthogrammica crude extract has an inhibitory effect on the proliferation of human lung cancer SPC-A1 cells.