The invention concerns an intramedullary nail to be inserted into a fractured long bone, for example a femur, comprising: a rod (2) extending between a proximal part (3) and a distal part (4); a tubular sleeve (5) into which said rod (2) is inserted coaxially; at least a first pair of expansion means (12) located in the distal part (4) of said rod (2), said expansion means (12) being made of a shape-memory material in order to assume a first configuration of rest in which they are disposed inside recesses in the lateral wall of the nail (1), and a second configuration of use in which said means (12) are located projecting from the lateral wall of the nail (1); slots (55) are present on the tubular sleeve (5) in correspondence with the shape-memory means (12) to allow for the fastening onto the bone when the means assume said second configuration of use; where said rod (2) comprises in correspondence with the proximal end (3) a transversal channel (6) for the passage of a stop screw (S), said tubular sleeve (5) comprising a pair of opposite apertures (7a, 7b) placed in alignment with said channel (6); and where the distal part (4) of the rod (2) does not have any through-channel for a screw.