Abstract： Objective To study the inhibitory effect on the expression of regulated upon activation,normal T cell expressed and secreted (RANTES) and monocyte ehemotactic activity of ectopic endometrial stromal cells by nuclear factor(NF)-kB decoy oligonucleotides (ODN). Methods The stromal cells of ectopic endometrium were divided into 3 groups. Two groups were cultured with or without 10 μg/L of interleukin (IL)-1β. Another group was transfected with NF-kB decoy ODN with the aid of a lipofectamine reagent. After 4 h of transfection, 10 μg/L of IL-1β was added to induce the stromal cells to secrete RANTES. Concentration of RANTES in the supernatant at 4, 8, 12, 24 and 36 h was measured with the sandwich enzyme linked immunosorbent assay (ELISA). U937 monocyte chemotactic activity was assayed in Boyden chambers. The specific RANTES-neutralizing monoclonal antibodies at serial doses (0. 5, 1, 2, 4and 8 mg/L) were added into IL-1β induced medium of 24 h to detect the monocyte chemotactic activity of RANTES in supernatant. Results The concentration of RANTES secreted by stromal cells was respectively (58 ± 10), ( 150 ± 35 ), ( 360 ± 46 ) and ( 586 ± 42 ) ng/L after IL-1β stimulation for 8,12,24 and 36 h,significantly higher than that of stromal cells cultured without IL-1β. The concentrations of RANTES were respectively (86±16), ( 128±28 ) and ( 183±32) ng/L after IL-1β stimulation for 12, 24 and 36 h in stromal cells transfected with NF-kB decoy ODN, evidently lower than that of stromal cells stimulated with IL-1β alone. The monocyte ehemotactic index of 12, 24, 36 h in conditioned medium of stromal cells transfected with NF-kB decoy ODN was respectively 10. 3 ± 0. 9, 13.7 ± 1.1, 18.6 ± 1.2, which was evidently lower than that of stromal cells stimulated with IL-1β alone. The anti-RANTES antibody at 0. 5, 1,2, 4 and 8 mg/L inhibited respectively 5%, 23%, 40%, 62% and 61% of the chemotactic activity in 12 h medium treated with IL-1β. Conclusions RANTES accounts for the majority of the monocyte chemotactic activity in IL-1β induced medium of 24 h. NF-kB decoy ODN may influence the feed-forward inflammatory loop whereby IL-1β from activated macrophages can lead to RANTES production by ectopic implants and further monocyte chemotaxis.