Background:Endometrial receptivity plays a key role in the establishment of successful implantation and its impairment may contribute to subfertility and limit the assisted reproduction techniques (ART) success.Objective: The aim of present study was to investigate endometrial receptivity in terms of β3 integrin, calcitonin and plexin-B1 expression in women with unexplained infertility. Materials and Methods:We evaluated expression of β3 integrin, calcitonin and plexin-B1 through mRNA level measurement with real-time RT-PCR, in the endometrium of 16 infertile women with unexplained infertility and 10 fertile women. Endometrial biopsies were collected during a single menstrual cycle on postovulatory day LH+7 in each subject. Results:Significant differences regarding β3 integrin and calcitonin expression levels found between patients with unexplained infertility and the fertile women. Endometrial plexin-B1 expression levels showed no significant difference between fertile and infertile women. There were significant correlations between expression of β3 integrin with calcitonin and plexin-B1 in fertile and infertile women. Conclusion:Reduced in endometrial expression of β3 integrin and calcitonin alone or together may contribute to unexplained infertility and these genes could account as the potential molecular markers of infertility.