Abstract: The contents of toosendanin in plant of the Melia genus collected in different parts of China was analysed by means of HPLC. The samples of barks, fruits and leaves of Melia azedarach and M. toosendan were from Shandong, Shaanxi, Hubei, Huna, Guangdong, Sichuan, Henan, Zhejiang, and Guizhou Provinces. The collected samples were air dried. Water was used for extraction. The extracts, after removal of the fat with petroleum ether, were partitionated in chloroform. The chloroform portion of fruit and leaf extracts were further purified by column chromatography. The chloroform or purified chloroform portions were then analysed by HPLC. Results showed that the content of tooendanin in M. azedarach or in M. toosendan varies with different region of origin. The bark of M. azedarach growing in Yanhe, Guizhou Province, Xixiang, Shaanxi Province and that of M. toosendan growing in Fugou, Henan Province were found to contain the highest amount of toosendanin among the tested samples (5.160, 4.679 and 4.223mg/g, respectively). Results of HPLC analyses also showed, the constituents of the bark of the plants growing in different regions vary greatly. Much less toosendanin was found in the fruits than in the bark of M. azedarach and M, toosendan with the exception of M. toosendan fruits collected in Hangzhou, Zhejing Province, which had higher content of toosendanin than that in the bark (0.800 and 0.574 mg/g, respectively). No toosendanin was found in the leaves of these two plant species and the samples of other nine Meliaceous plants other than Melia genus.