Introduction Per menopausal bleeding (PMB) occurs in approximately 3%of women and it is the usual presenting symptom of endometrial carcinoma in approximately 93% of cases. About 5–15% of per menopausal women with abnormal bleeding may have endometrial cancer. A reliable and minimally invasive method is needed to identify or exclude those cases. The tumor environment is highly hypoxic so that cancer cells have an intensified anaerobic metabolism. Cancer cells use anaerobic pathways for energy acquisition even in the presence of oxygen, a phenomenon described as "anaerobic glycolysis". The lactate released by this anaerobic metabolism passes outside the cancer cells leading to the acidification of the extracellular matrix. This is responsible for the development of aggressive malignant phenotype as low pH enhances cancer cell invasive and metastatic ability. Aim of the work: This study was done to show the role of serum lactate dehydrogenase and endometrial thickness in the detection of endometrial carcinoma. Material and methods: This study was carried out at Tanta University hospital, Obstetrics and Gynecology Department, in the period from April 2017 to December 2018. This study included 90 women with perimenopausal bleeding admitted to Obstetrics & Gynecology Department at Zagazig University Hospital. All cases were subjected to full history, full clinical examination, transvaginal sonography, serum LDH and Diagnostic endometrial biopsy was taken for histopathological examination. Result: In this study, endometrial thickness at 11.5mm cut off value showed 80.6% sensitivity, 53.7% specificity, PPV 53.7%, NPV 80.5%and diagnostic accuracy 64.4%. It was found that TVS evaluation of endometrial thickness is not sensitive enough to detect cancer of the endometrium and therefore, could not replace histological evaluation of the endometrial tissue in women with postmenopausal bleeding. LDH level cutoff value of 430 U/L could differentiate malignant from benign lesions with a sensitivity of 80.6%, specificity 57.4%, PPV 55.7% and NPV 81.5% with a diagnostic accuracy of 66.7%. Thus, total serum LDH can be used as a good negative test using the cut-off level (430 U/L). Combination of evaluation of endometrial thickness by TVS (with specificity of 53.7% and accuracy of 64.4%) and serum LDH (with specificity of 57.4% and accuracy of 66.7%) increase the specificity to 72.2%. also increase the accuracy to 67.7%. Conclusion: measurement of serum LDH is considered another simple method to be combined with TVS if endometrial cancer is suspected. However, further studies are needed using LDH isoenzymes profile and TVS endometrial morphology.