A profile for making frames for sliding doors/windows including a fixed frame defined by two horizontal members (3, 4) and two vertical members (5, 6), one profile defining at least one first bottom horizontal member for said frame and comprising two parallel sliding tracks (8, 9) made on a bottom base element; - a cavity or seat formed in the profile through its full depth, extending transversally of the tracks (8, 9) and adapted to stably accommodate - a thermal insulation or thermal break element, a part of which is shaped to match the cavity or seat and which also acts on at least one part of the tracks (8, 9); - thermal insulation means acting longitudinally along the full length of the bottom element of the profile and acting also on the tracks (8, 9); characterised in that the profile (7, 7') comprises, in cross section, a base portion (10, 10') and two pairs of arms (14, 15) protruding vertically, and transversal to the base portion (10, 10'), each pair (14, 15), constituting the body of the respective track (8, 9), each of the thermal insulation means (13, 13') being comprised of a first and second flat rods (13a, 13b) made of a thermally insulating material for each track (8, 9); the two rods in each pair (13a, 13b) being parallel to each other and positioned, respectively, the first rod at the base of one of the pairs of arms (14, 15), and the second rod under the first rod and at the bottom zone of the base portion (10, 10'); each rod (13a, 13b) being bilaterally associated with the profile (7, 7') through respective coupling grooves (16, 17); the thermal insulation means (13, 13') being also embodied by the tracks (8, 9) comprising, on the pairs of track arms (14, 15), respective internal supports (8i, 9i), each in the shape of an upturned U fitted between each pair of arms (14, 15) and having a rounded head (8t, 9t); each track (8, 9) made in this way being a single block made of thermal insulating material. - a cavity or seat formed in the profile through its full depth, extending transversally of the tracks (8, 9) and adapted to stably accommodate - a thermal insulation or thermal break element, a part of which is shaped to match the cavity or seat and which also acts on at least one part of the tracks (8, 9); - thermal insulation means acting longitudinally along the full length of the bottom element of the profile and acting also on the tracks (8, 9); characterised in that the profile (7, 7') comprises, in cross section, a base portion (10, 10') and two pairs of arms (14, 15) protruding vertically, and transversal to the base portion (10, 10'), each pair (14, 15), constituting the body of the respective track (8, 9), each of the thermal insulation means (13, 13') being comprised of a first and second flat rods (13a, 13b) made of a thermally insulating material for each track (8, 9); the two rods in each pair (13a, 13b) being parallel to each other and positioned, respectively, the first rod at the base of one of the pairs of arms (14, 15), and the second rod under the first rod and at the bottom zone of the base portion (10, 10'); each rod (13a, 13b) being bilaterally associated with the profile (7, 7') through respective coupling grooves (16, 17); the thermal insulation means (13, 13') being also embodied by the tracks (8, 9) comprising, on the pairs of track arms (14, 15), respective internal supports (8i, 9i), each in the shape of an upturned U fitted between each pair of arms (14, 15) and having a rounded head (8t, 9t); each track (8, 9) made in this way being a single block made of thermal insulating material.