The illegal killing and taking of wild birds remains a major threat on a global scale. However, there are few quantitative data on the species affected and countries involved. We quantified the scale and scope of this issue in Northern and Central Europe and the Caucasus, using a diverse range of data sources and incorporating expert knowledge. The issue was reported to be widespread across the region and affects almost all countries/territories assessed. We estimated that 0.4–2.1 million birds per year may be killed/taken illegally in the region. The highest estimate of illegal killing in the region was for Azerbaijan (0.2-1.0 million birds per year). Out of the 20 worst locations identified, 13 were located in the Caucasus. Birds were reported to be illegally killed/taken primarily for sport and food in the Caucasus and for sport and predator/pest control in both Northern and Central Europe. All of the 28 countries assessed are parties to the Bern Convention and 19 are also European Union Member States. There are specific initiatives under both these policy instruments to tackle this threat, yet our data showed that illegal killing and taking is still occurring and is not restricted to Mediterranean European countries. Markedly increased effort is required to ensure that existing legislation is adequately implemented and complied with/enforced on the ground. Our study also highlighted the paucity of data on illegal killing and taking of birds in the region. It is a priority, identified by relevant initiatives under the Bern Convention and the European Union, to implement systematic monitoring of illegal killing and taking and to collate robust data, allowing stakeholders to set priorities, track trends and monitor the effectiveness of responses.