A bacterial strain, JCR5, which degrades 17alpha-ethynylestradiol (EE2), was isolated from activated sludge of wastewater treatment plant treating wastewater from pharmacy factory mainly producing contraceptive medicine in Beijing, China. Based on its morphology, physiology biochemical properties and 16S rDNA sequence analysis, this strain was identified as Sphingobacteriumn sp. JCR5. Strain JCR5 can grow on EE2 as sole carbon and energy source. The degradation process for EE2 with initial concentration of 30 mg x L(-1) was studied, and the result indicated that the degradation rate of EE2 within 10 days was 87%. Experiments of different substrates showed that strain JCR5 can grow on many substrates other than EE2 such as several steroidal estrogens (estrone, 17beta-estradiol, estriol and mestranol), the intermediates in contraceptive medicine processing and some aromatic compounds. Mass spectrum analysis demonstrated that EE2 was oxygenized to estrone (E1) firstly, and 2-hydroxy-2,4-dienevaleric acid and 2-hydroxy-2,4-diene-1, 6-dioic acid were the main catabolic intermediates during EE2 degradation. The former adopted a pathway that was analogical to the pathway of the previously reported testosterone-degrading Comamnonas testosteroni TA441, and the latter was a metabolite with a different cleavage position of 3-hydroxy-4,5-9, 10-disecoestrane-1(10), 2-diene-5,9, 17- trione-4-oic acid from the former.