OBJECTIVE Recent evidence of growth hormone (GH) receptor expression in rat endometrium and human myometrium have focused our attention on the role of the GH in endometrial development. We tested the expression of GH in the human endometrium throughout the menstrual cycle and during pregnancy. METHODS Immunohistochemical study was performed on endometrial specimens of fertile women in different periods of the menstrual cycle and in decidua of pregnant women. RESULTS Glandular cells of the human endometrium were positive for GH in the mid and late luteal phase. Furthermore, the glandular cells of decidua showed intense staining for GH, while the stromal cells were negative. No immunostaining was expressed in the proliferative or early luteal phase. The intensity levels of staining for GH in decidual specimens were significantly higher than in glandular cells of secretory endometrium specimens (P < 0.01). CONCLUSIONS The glandular cells of the human endometrium express GH from the late luteal phase throughout pregnancy in the decidual tissue. We suppose that GH plays an important role in blastocyst implantation.