We observed a higher CD8+/PD-1 : CD8+/PD-L1+ T cell ratio in patients with dysmenorrhea (7.35 ± 5.14, median 6.76, Min–Max 1.5–24.2) compared with other endometriosis patients (3.24 ± 1.46, median 2.99, Min–Max 1.5–5.6) (p = 0.028). Here, PDCD1 is linked to endometriosis.