In the present study, we aimed to examine whether hypothyroidism affected the endometrial receptivity of adult female rats by particularly evaluating the changes in the histology of the endometrium, and regulation of thyroid-stimulating hormone (TSH), free T4 (FT4), progesterone, estrogen (E2), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) from different aspects. This evidence concerns the gene PLOD1 and hypothyroidism.