The invention discloses a use of miR-199a-5p as a biomarker for diagnosis of endometriosis. The invention also discloses another use of miR-199a-5p of manufacturing a drug for improving endometriosis.一種微小RNA miR-199a-5p之用途,係以該微小RNA miR-199a-5p之表現程度作為生物標記,用以診斷子宮內膜異位症,該微小RNA miR-199a-5p另用以製備治療子宮內膜異位症之藥物