On September 6, 2008, bluetongue was detected for the first time in Sweden. Intensified active surveillance in cattle and vector surveillance, prompted by the situation in northern Europe, preceded the detection. A vaccination campaign and intensive surveillance activities were initiated nationally, but with a focus on the southern part of the country. Measures included both active and passive surveillance by serology and PCR in ruminants, along with vector surveillance. The investigations revealed that the infection occurred over a large area of southern Sweden during September and October 2008, despite comparatively low vector activity, an apparently low viral load and no clinical disease. Transplacental infection was detected in one case.