International audienceIn most countries, passengers' rail transportation is characterized by a monopoly. Nevertheless, it does not mean that the monopolist-usually the national company-does not face competition, in the form of intermodal competition (planes, cars). This article focuses on the French national rail company (SNCF) that still has a monopoly on national passenger traffic. It analyses SNCF's pricing behavior on most of the origin/destination pairs it operates with high speed trains to/from Paris. It takes into account the fact SNCF enjoys a limited leeway to set its prices because ticket prices are still regulated in France. The existence of such a price cap regulation is an opportunity for an economist to analyse how a transport...