Endometriosis is a common condition, affecting 10-15% of reproductive age women. Current treatments are not consistently effective and have troublesome side effects. Here, we propose to make a long-acting treatment for endometriosis by the slow release of levonorgestrel from polymer implants composed of a safe and degradable polymer called poly(PDL-co-DO). Placement of a slow-release device in the intraperitoneal space would allow for treatment that lasts several years.  We have preclinical data supporting this concept in mice.  Here, we will advance this technology by scaling up production of implants and testing in a proven endometriosis model in non-human primates.