Thin endometrium (TE) is defined as an endometrial thickness of ≤7 mm during the mid-luteal phase. TE can impair endometrial tolerance, reducing embryo implantation and pregnancy rates, and is associated with poor outcomes in assisted reproductive treatments. This review summarizes the causes, mechanisms, and treatments of TE. TE is caused by hormonal changes, uterine cavity factors, and other unknown factors. Treatments include pharmacological therapies (hormonal and vasoactive drugs), regenerative medicine, intrauterine infusion of growth factors and platelet-rich plasma, and complementary therapies. However, the mechanisms of these treatments are not fully understood. Various approaches are being explored to improve treatment outcomes in TE patients. TE is characterized by poor endometrial growth, reduced blood flow, and decreased vascularization. The causes of TE include inflammatory, medical, and idiopathic factors. TE is associated with reduced embryo implantation and pregnancy rates, and increased miscarriage risks. Treatments for TE include estrogen therapy, growth hormone, human chorionic gonadotropin, gonadotropin-releasing hormone agonists, and tamoxifen. These treatments aim to improve endometrial thickness and pregnancy outcomes. Stem cell therapy, including mesenchymal stem cells, adipose-derived stem cells, and endometrial stem cells, is a promising treatment for TE. Stem cells can promote endometrial repair and regeneration. Extracellular vesicles and exosomes are also being explored for their potential in improving endometrial function. Autologous platelet-rich plasma is another treatment that can improve endometrial thickness and pregnancy outcomes. Complementary and alternative therapies, such as acupuncture and traditional Chinese medicine, are also being studied for their potential in treating TE. These therapies may improve endometrial tolerance and pregnancy outcomes. However, more research is needed to determine the most effective treatments for TE. Overall, TE remains a significant challenge in reproductive medicine, and further research is needed to develop more effective treatments.Thin endometrium (TE) is defined as an endometrial thickness of ≤7 mm during the mid-luteal phase. TE can impair endometrial tolerance, reducing embryo implantation and pregnancy rates, and is associated with poor outcomes in assisted reproductive treatments. This review summarizes the causes, mechanisms, and treatments of TE. TE is caused by hormonal changes, uterine cavity factors, and other unknown factors. Treatments include pharmacological therapies (hormonal and vasoactive drugs), regenerative medicine, intrauterine infusion of growth factors and platelet-rich plasma, and complementary therapies. However, the mechanisms of these treatments are not fully understood. Various approaches are being explored to improve treatment outcomes in TE patients. TE is characterized by poor endometrial growth, reduced blood flow, and decreased vascularization. The causes of TE include inflammatory, medical, and idiopathic factors. TE is associated with reduced embryo implantation and pregnancy rates, and increased miscarriage risks. Treatments for TE include estrogen therapy, growth hormone, human chorionic gonadotropin, gonadotropin-releasing hormone agonists, and tamoxifen. These treatments aim to improve endometrial thickness and pregnancy outcomes. Stem cell therapy, including mesenchymal stem cells, adipose-derived stem cells, and endometrial stem cells, is a promising treatment for TE. Stem cells can promote endometrial repair and regeneration. Extracellular vesicles and exosomes are also being explored for their potential in improving endometrial function. Autologous platelet-rich plasma is another treatment that can improve endometrial thickness and pregnancy outcomes. Complementary and alternative therapies, such as acupuncture and traditional Chinese medicine, are also being studied for their potential in treating TE. These therapies may improve endometrial tolerance and pregnancy outcomes. However, more research is needed to determine the most effective treatments for TE. Overall, TE remains a significant challenge in reproductive medicine, and further research is needed to develop more effective treatments.