A method of evaluating at least one quantity relating to the distortion of a nuclear fuel assembly, the method including the following steps: the nuclear fuel assembly is placed in a volume of water bounded by an upper free surface; a camera is placed outside the volume of water, above the free surface; at least one image of at least one lateral face of the nuclear fuel assembly is taken; the at least one image is analyzed graphically and the at least one quantity relating to the distortion of the nuclear fuel assembly is deduced therefrom.