Automatic road marking system, comprising a pilot vehicle and an automatic guided vehicle AGV; said pilot vehicle comprising: - a first GPS module suitable for detecting the position of the pilot vehicle, - cameras (24a, 24b) directed towards the front in such way to take images of a width of a carriageway of a road surface, - a control unit connected to the first GPS module and to the cameras (24a, 24b) to receive data on the position of the vehicle detected by the first GPS module and on the images taken by the cameras (24a, 24b), - a wireless transmitter connected to the control unit to transmit the data received from the control unit, and - a tank suitable for being filled with road marking paint said AGV comprising: - a motor and a steering system, - a second GPS module suitable for detecting the position of the AGV, - spray nozzles (34a, 34b) suitable for spraying road marking paint on the road surface; - a hydraulic circuit hydraulically connected to the spray nozzles (34a, 34b) and to the tank of the pilot vehicle to supply the paint from the tank to the spray nozzle, and - an electronic control unit ECU connected to the motor, to the steering system of the AGV, to the second GPS module and to the hydraulic system, and - a receiver connected to the ECU of the AGV and coupled to the transmitter of the control unit of the pilot vehicle in order to receive data from the transmitter of the control unit of the pilot vehicle; said system also comprising: - a third GPS module suitable for being disposed in a fixed position in the proximity of the carriageway or in the carriageway where the road markings are to be made; and - a wireless transmitter connected to said third GPS module and coupled with said control unit of the pilot vehicle and with said ECU of the AGV to transmit data to the control unit of the pilot vehicle and to the ECU of the AGV, indicating the fixed position wherein the third GPS module is disposed. - a first GPS module suitable for detecting the position of the pilot vehicle, - cameras (24a, 24b) directed towards the front in such way to take images of a width of a carriageway of a road surface, - a control unit connected to the first GPS module and to the cameras (24a, 24b) to receive data on the position of the vehicle detected by the first GPS module and on the images taken by the cameras (24a, 24b), - a wireless transmitter connected to the control unit to transmit the data received from the control unit, and - a tank suitable for being filled with road marking paint said AGV comprising: - a motor and a steering system, - a second GPS module suitable for detecting the position of the AGV, - spray nozzles (34a, 34b) suitable for spraying road marking paint on the road surface; - a hydraulic circuit hydraulically connected to the spray nozzles (34a, 34b) and to the tank of the pilot vehicle to supply the paint from the tank to the spray nozzle, and - an electronic control unit ECU connected to the motor, to the steering system of the AGV, to the second GPS module and to the hydraulic system, and - a receiver connected to the ECU of the AGV and coupled to the transmitter of the control unit of the pilot vehicle in order to receive data from the transmitter of the control unit of the pilot vehicle; - a third GPS module suitable for being disposed in a fixed position in the proximity of the carriageway or in the carriageway where the road markings are to be made; and - a wireless transmitter connected to said third GPS module and coupled with said control unit of the pilot vehicle and with said ECU of the AGV to transmit data to the control unit of the pilot vehicle and to the ECU of the AGV, indicating the fixed position wherein the third GPS module is disposed.