Preoperative serum STIP1 levels in patients with endometriosis/adenomyosis were significantly higher than those in the controls (64.3 ± 5.5 ng/mL in the adenomyosis group, 64.4 ± 5.6 ng/mL in the endometriosis group, and 68.6 ± 10.5 ng/mL in the coexisting adenomyosis and endometriosis groups vs 22.8 ± 1.3 ng/mL in the controls, P < 0.001). Here, STIP1 is linked to endometriosis.