Therefore, the aims of the present study were (a) to assess leptin and OB-RL gene expression in ectopic and eutopic endometria of women with endometriosis and in eutopic endometrium of non-endometriosis controls, (b) to determine the leptin/BMI ratio in serum and PF in both groups, (c) to assess the immunoreactive presence of OB-RL in endometrium and endometriotic implants, and (d) to investigate the relationship among these variables. The gene discussed is LEP; the disease is endometriosis.