Abstract: An anti-siphoning device for preventing the siphoning of gasoline from the gasoline tank of a motor vehicle is disclosed. The device is formed in a helical spring construction having an upper cylindrical-shaped portion and a lower cone-shaped portion. The cylindrical-shaped portion is formed of a series of contiguous or "kissing" coils, and the cone-shaped portion is also provided with a series of contiguous coils at its lower end. The lower end of the cone-shaped portion is provided with a bend so that the contiguous coil portion at the lower end of the spring projects outwardly at an angle of approximately 45.degree. from the vertical axis of the device. The tips at the upper and lower ends of the device are formed so as to avoid any friction between adjacent surfaces which could cause sparks.