To minimise the negative ecological effects of soybean production, multi-stakeholders along the global soybean supply chain collaborated to develop, implement and verify a global certification standard called the Round Table on Responsible Soy (RTRS). RTRS certification is almost a quasi-mandatory sustainability standard; however, its potential trade effects remain poorly understood. Using a structural gravity model that exploits country variations in RTRS-certified production volumes and certified land areas, we assess the effect of RTRS certification on soybean trade flows. We show that RTRS certification reduces trade flows, especially exports to non-OECD countries. In essence, developing countries experience lower imports in response to standards than do developed countries. Thus, reconciling international trade with environmental sustainability goals remains a challenge.