Grenoble and Toulouse are the leading french urban innovation systems outside Paris. This paper analyses their genesis. Their story has two different sides : the scientific one and the industrial one. The scientific histories of the two towns are very similar since the creation of electrical institutes in the beginning of this century, but their industrial histories are very different. In Grenoble, sciencebased industry is very ancient and is from a long time connected with universities and science organizations. In Toulouse, science-based industry is the result of national policies and its connection with universities and laboratories came much later. Despite this difference, the two urban innovation systems are very similar now.