Abstract: Lysiphlebus testaceipes (Cresson) was Introduced from Oklahoma, U.S.A. to Shaanxi in 1983. Several aphid species, including Schizaphis graminum, Aphis gossypii, A. craccivora, A-rumicie, Rhophlosiphum padi, and R. maidis were found to be the hosts of the parasitoid. During 1983-1986, a total number of 21,307, 11,508, 2,933 and 19,562 of the parasitoids were released on cotton, wheat, wasted weedy lands, and three greenhouses of the Xian Botanical Garden, respectively. Results of the recovery samples in 1987 were: no L. testaceipes from the 172 parasitized aphids of the cotton fields; one emerged from 34 S. graminum and one from 314 R. padi of the wheat fields; 6 from 420 A. Craccivora of the weedy lands. The aphid parasitization on two ornamentals, Hibiscus rosea-sinensis and Pittosporum tobira in the greenhouses were 49. 3% and 32.2%, respectively, all the emerged parasitoids were L. testaceipes. Factors influencing the establishment of the introduced parasite in Shaanxi is also discussed.