Based on an analysis of the literature, we suspect that the regulation of IL-17 on ectopic endometrial is mainly likely to trigger its invasion, implantation, growth and proliferation during the early stage of disease, that is IL-17 might be more important in the initiation, but not in the later process of endometriosis 64, 114, 85. The gene discussed is IL17A; the disease is endometriosis.