We estimate whether Okun's law holds for a large sample of emerging market and high-income countries. Our aim is to research whether similar relationship holds be-tween GDP growth and unemployment in countries with different income levels and/or institutional quality. To ensure the robustness of the results, institutional quality is measured by a variety of indicators, such as the World Bank Doing Business indicators and the Transparency International’s corruption perception index. The special focus of the analysis is on the largest emerging market countries, including China, as their im-portance for the global economy is the greatest. We find that there is relationship be-tween GDP growth and unemployment also in the emerging market countries, but the evidence is less clear than in the case of high-income countries. Furthermore, in China it is difficult to ascertain the existence of Okun’s law, and reasons for this finding are discussed. Last, the relationship between GDP growth and unemployment seems to change as countries' income levels grow.