Nest re-use in a high density population of Magpies Pica pica in the city of Sofia and its vicinity was studied during 1999–2000. The rate of nest re-use was significantly higher within the urban area (17%) as compared to the immediate rural surroundings within the distance of 1 km (7%). Re-used nests were on average higher above the ground than newly-built nests. The nest reuse rate was not related to breeding density, abundance or the mean height of available trees. Magpies re-using their old nests laid eggs significantly earlier compared to those building new nests. However, nest re-use did not confer other benefits on the reproductive output since clutch-size, hatching and fledging success did not differ significantly between the two nesting strategies.