Although these three cytokines/chemokines identified in our study have so far not been sufficiently investigated in endometriosis our experimental data link changes in concentrations of these proteins to peritoneal endometriosis, which implies that CCL1, CCL3 and CCL21 might have a role in the aetiology and pathogenesis of this type of endometriosis. Here, CCL21 is linked to endometriosis.