Objective(s): To explored the antifertility effectiveness and influence on the endometrium of a micro-copper/low-density polyethylene/methyl vinyl silicone rubber (Cu/LDPE/MVQ) composite in rhesus macaques. Study design: Healthy reproductive aged female rhesus macaques underwent abdominal hysterotomy for surgical placement of either the experimental Cu/LDPE/MVQcomposite (Cu/LDPE/MVQ n=5), bare copper wire (Cu, n=5), or hysterotomy only sham-operation group [(SOI, n=4), (SOII, n=6)]. Females in the Cu/LPDE/MVQ, Cu, and SOI groups were housed with fertile males for approximately three menstrual cycles. We assessed pregnancy by hysterectomy. Females in the Cu/LDPE/MVQ, Cu, and SOII groups underwent hysterectomy at about 4 months post-insertion for histologic assessment of morphologic changes of the endometrium, evaluation of materials using scanning electron microscopy (SEM), and evaluation of the inflammatory markers, including substance P receptor (SPR), associated with endometrial bleeding using enzyme linked immunosorbent assay, quantitative RT-PCR, and Western blot analyses. Results: All of the SOI group females became pregnant (4/4,100%). In contrast, no pregnancies occurred in either the Cu/LDPE/MVQ (0/5, 0%) or Cu (0/5, 0%) groups. We observed histologic features consistent with chronic endometrial inflammation in all females of the Cu group, but none of the SOII or Cu/LDPE/MVQ animals. Levels of inflammatory markers were significantly increased in the Cu group, compared with SOIL or Cu/LDPE/MVQ groups (p<.05). SEM showed evidence of corrosion in the Cu wire not seen in the Cu/LDPE/MVQ group. Conclusion(s): Cu/LDPE/MVQ material provided a contraceptive effect similar to Cu in macaques, with a lower impact on inflammation and inflammatory markers of the endometrium. (C) 2019 Elsevier Inc. All rights reserved.