Illkirch-Graffenstaden is a commune in the Bas-Rhin department in Alsace in north-eastern France. It is the second-largest suburb of the city of Strasbourg, and is adjacent to it on the south-southwest. Illkirch-Graffenstaden is one of the fastest growing cities in France and probably in Europe, its population having more than doubled in less than forty years (from 11,648 in 1968 to 26,368 in 2006).

In the past Illkirch and Graf(f)enstaden were two separate villages. Illkirch-Graffenstaden therefore differs from more conventional towns, being akin to two long villages, one to the north of the other, giving rise to an exceptionally long main street lined with traditional small half-timbered houses: where these have been supplemented by modern designs, the modern buildings tend to respect the traditional size and look of the older ones.