To identify patients with Lynch syndrome and triage them for germline mutational analysis, MMR-IHC (plus MLH1 promoter methylation status analysis in the case of immunohistochemical loss of MLH1/PMS2 expression) or MSI testing should be performed in all endometrial carcinomas, regardless of the histological subtype of the tumor (III, B). The gene discussed is MLH1; the disease is endometrial carcinoma.