The present invention relates to devices and to a method for protection against guiding loss for a guided vehicle provided with a guide member including two V-mounted guide rollers (1, 2), i.e. a first roller (1) and a second roller (2), which are to engage with a first rolling surface (7A) and a second rolling surface (7B) of a guide rail (3), respectively, said first and second rolling surfaces (7A, 7B) being located on either side of a longitudinal median plane (M) of said guide rail (3), each of the rollers being provided with a flange (10), said flanges (10) freely clamping onto the guide rail (3), wherein the protection devices include: a profile member (72) having a height h>0 extending longitudinally and being configured to be attached along the length thereof onto at least a portion of said guide rail (3) between said first and second rolling surfaces (7A, 7B), said profile member (72) having a section suitable for guiding the guide member upon a derailment or guiding loss of said guide member when said profile member (72) is attached to said portion of the guide rail (3), wherein said section has a shape suitable for retaining the flange (10) of the first roller (1) on the side of the median plane (M) that includes the rolling surface (7A) of said first roller (1), and the flange (10) of the second roller (2) on the side of the median plane (M) including the rolling surface (7B) of said second roller (2); and a means (73) for attaching said profile member onto said guide rail (3).