Innovation, intellectual property, growth The paper explores the consequences of product innovation with patents protection, in an endogenous growth framework. New goods are temporarily monopoli stic and old ones are competitive. Competitive equilibrium is not optimal because of external effets of innovation, and price distorsions induces distorsions in the allocation of ressources. The competitive growth rate may be lower or higher than the optimal one. Public authorities have two means of action : length of patents, and taxes or subsidies to firms. A statistical test on US patents data shows that technological innovation is endogenous.Innovation, propriété intellectuelle, croissance Cet article explore les conséquences de l'innovation ...