A system for determining the number of persons in a vehicle, wherein said system comprises: - at least one first optical detector with a first optical axis (Δ 1) and a first angular field of view; - at least one second optical detector with a second optical axis (Δ 2) and a second angular field of view, wherein the first optical axis and the second optical axis are secant and form an angle of between approximately 20° and approximately 130°, so that the first field of view and the second field of view are different and at least partially overlap; - a detection module configured to trigger the acquisition of at least a first image of the vehicle (Im 1) by said first optical detector and of at least a second image of the vehicle (Im 2) by said second optical detector when the vehicle enters a predetermined control zone, resulting in at least a first set (S 1) of images (Im 1, Im 2) of the vehicle acquired with different fields of view; wherein the system for determining the number of persons is characterised in that it comprises: - a processing unit configured to: - detect in said at least one first image (Im 1) and said at least one second image (Im 2) of said at least one first set of images, one or more persons and coordinates (411 - 414, 421 - 424) in the image of said person or persons; - determine, by epipolar geometry, from the coordinates (411 - 414) of each of said persons detected in said at least one first image (Im 1) of the set of images, the corresponding coordinates of said person in said at least one second image (Im 2) of the set of images; - determine whether said corresponding coordinates are the coordinates (421 - 424) of a person detected in said at least one second image (Im 2); - in the affirmative, deduce that there is a similarity between said person detected in said at least one first image (Im 1) of the set of images and said person detected in said at least one second image (Im 2) of the set of images; - determine, on the basis of the similarities thus determined between said person or persons detected in said at least one first image (Im 1) and said person or persons detected in said at least one second image (Im 2) of the set of images, the number of persons in the vehicle. - at least one first optical detector with a first optical axis (Δ 1) and a first angular field of view; - at least one second optical detector with a second optical axis (Δ 2) and a second angular field of view, wherein the first optical axis and the second optical axis are secant and form an angle of between approximately 20° and approximately 130°, so that the first field of view and the second field of view are different and at least partially overlap; - a detection module configured to trigger the acquisition of at least a first image of the vehicle (Im 1) by said first optical detector and of at least a second image of the vehicle (Im 2) by said second optical detector when the vehicle enters a predetermined control zone, resulting in at least a first set (S 1) of images (Im 1, Im 2) of the vehicle acquired with different fields of view; wherein the system for determining the number of persons is characterised in that it comprises: - a processing unit configured to: - detect in said at least one first image (Im 1) and said at least one second image (Im 2) of said at least one first set of images, one or more persons and coordinates (411 - 414, 421 - 424) in the image of said person or persons; - determine, by epipolar geometry, from the coordinates (411 - 414) of each of said persons detected in said at least one first image (Im 1) of the set of images, the corresponding coordinates of said person in said at least one second image (Im 2) of the set of images; - determine whether said corresponding coordinates are the coordinates (421 - 424) of a person detected in said at least one second image (Im 2); - detect in said at least one first image (Im 1) and said at least one second image (Im 2) of said at least one first set of images, one or more persons and coordinates (411 - 414, 421 - 424) in the image of said person or persons; - determine, by epipolar geometry, from the coordinates (411 - 414) of each of said persons detected in said at least one first image (Im 1) of the set of images, the corresponding coordinates of said person in said at least one second image (Im 2) of the set of images; - determine whether said corresponding coordinates are the coordinates (421 - 424) of a person detected in said at least one second image (Im 2); - in the affirmative, deduce that there is a similarity between said person detected in said at least one first image (Im 1) of the set of images and said person detected in said at least one second image (Im 2) of the set of images; - determine, on the basis of the similarities thus determined between said person or persons detected in said at least one first image (Im 1) and said person or persons detected in said at least one second image (Im 2) of the set of images, the number of persons in the vehicle.