To investigate if the peritoneal source of TGF-β1 or its signalling components, TGF-βR1, TGF-βR2 and Smad3, are altered in women with endometriosis, we quantified mRNAs encoded by TGFB1, TGFBR1, TGFBR2 and SMAD3. Notably TGFB1 mRNAs were significantly increased (p<0.05) in peritoneum adjacent to endometriosis lesions when compared to peritoneum that was distal to the lesion (Figure 3B), but there was no change in TGFB1 expression between women with endometriosis and those without (Figure 3C) or between sites of peritoneum in women without disease (Figure 3A). The gene discussed is TGFBR1; the disease is endometriosis.