A method for establishment of a new well path from an existing well, wherein the existing well, at least in a portion where the new well path is to be established, is delineated radially by a casing, and wherein the method comprises the following steps: disposing and anchoring a plug base in the well; providing and setting a plug above the plug base in the well and along a longitudinal section thereof, wherein the plug covers substantially the entire cross-section of the well, including an annulus between the casing and a surrounding formation; after having set the plug in the well, removing a portion of the plug in such a manner that at least a cross-sectional section of the plug remains on the outside of the casing; disposing and anchoring a direction-guiding element in the well, and at least partially within the longitudinal section; and by means of the direction-guiding element, guiding a drilling tool against the inside of the casing in the existing well path in order to form a hole through the casing, and through the remaining cross-sectional section of the plug within the longitudinal section, which opens up to formation of a new well path, wherein step also comprises the following sub-steps: conducting a perforation tool down into the casing and to the longitudinal section where the plug is to be set; forming holes in the casing and along the longitudinal section by means of the perforation tool; and pumping a fluidized plugging material down through a string and out into the casing, thus also into the annulus outside the casing via the holes in the casing, whereby said plug is formed along the longitudinal section. disposing and anchoring a plug base in the well; providing and setting a plug above the plug base in the well and along a longitudinal section thereof, wherein the plug covers substantially the entire cross-section of the well, including an annulus between the casing and a surrounding formation; after having set the plug in the well, removing a portion of the plug in such a manner that at least a cross-sectional section of the plug remains on the outside of the casing; disposing and anchoring a direction-guiding element in the well, and at least partially within the longitudinal section; and by means of the direction-guiding element, guiding a drilling tool against the inside of the casing in the existing well path in order to form a hole through the casing, and through the remaining cross-sectional section of the plug within the longitudinal section, which opens up to formation of a new well path, wherein step also comprises the following sub-steps: conducting a perforation tool down into the casing and to the longitudinal section where the plug is to be set; forming holes in the casing and along the longitudinal section by means of the perforation tool; and pumping a fluidized plugging material down through a string and out into the casing, thus also into the annulus outside the casing via the holes in the casing, whereby said plug is formed along the longitudinal section. conducting a perforation tool down into the casing and to the longitudinal section where the plug is to be set; forming holes in the casing and along the longitudinal section by means of the perforation tool; and pumping a fluidized plugging material down through a string and out into the casing, thus also into the annulus outside the casing via the holes in the casing, whereby said plug is formed along the longitudinal section.