Approaches to the treatment of endometriosis vary worldwide, but studies comparing endometriosis medications in different ethnic groups are rare. A systematic literature search identified two studies directly comparing dienogest (DNG) versus gonadotropin-releasing hormone (GnRH) analogues in European and Japanese populations. Meta-analysis of visual analogue scale scores revealed no heterogeneity in response between the trials, indicating equivalent efficacy of DNG and GnRH analogues for endometriosis-related pain across populations. DNG was significantly superior to GnRH analogues for bone mineral density change in both trials, but significant heterogeneity between the studies may indicate ethnic differences in physiology.