To investigate the involvement of EMT and TGF-β1/SMAD2 signalling pathway in the development of endometriosis, IHC and western blot analyses of E-cadherin, vimentin, TGF-β1, SMAD2, and phospho-SMAD2 expression were performed on eutopic and ectopic endometria of endometriosis and on normal endometrial tissue. The gene discussed is TGFB1; the disease is endometriosis.