Abstract: OBJECTIVE To analyze the volatile components in ethanol extract from seeds of Pittosporum tobira Ait.(EESPTA) and investigate the anti-endotoxin activity of EESPTA in vitro. METHODS The volatile components in EESPTA were extracted with steam distillation method and then analysized by GC-MS. The relative content of each component was calculated by peak area normalization. The anti-endotoxin activity of EESPTA in vitro was investigated by CEPTAL (chromogenic end-point tachypleus amebocyte lysate assay). RESULTS The 32 peaks were detected and then identified preliminary, which made up 99.82% of the total volatile components. The anti-endotoxin activity of EESPTA in vitro was observed in concentration-dependent manner from CEPTAL assay. The highest content constituent was 1R,4S,7S,11R-2,2,4,8-tetramethyltricyclo5.3.1.0(4,11) undec-8-ene (54.78%), and other relative high content constituents were 2-methylene-cholestan-3-ol(7.27%), humulane-1, 6-dien-3-ol(6.23%), 4-methyl-5-decanol(4.11%), viridiflorol(3.86%), Alloaromadendrene (3.80%), 2-methyl-2-butenoic acid(3.50%), et al. CONCLUSION EESPTA has obvious anti-endotoxin activity with a concentration dependence. This study provides a scientific basis for further development and utilization of Pittosporum tobira Ait..