A system for snap fixing of guides, particularly for sliding of doors of pieces of furniture, adapted to avoid all traditional systems for fixing said guides with screws of any type, whereby it provides for a preliminary step of preparing the outer surfaces of the top and footing of the piece of furniture, with the application of elastic hook- or claw-shaped clips (10,20) of the system, with subsequent application of the upper and lower profiles (30, 40) of the system, where: - the upper profile comprises at least one pair of longitudinal guides for the application of the pairs of pulleys for the sliding support of the door wherein the upper profile provides for a first step of adjacent arrangement and insertion of its claw-shaped edge in the series of clips of the top, then a second step of rotation of said upper profile until it touches the outer surface of the top, with simultaneous snap action for the insertion of its opposite edge against a series of heads or pins, of the system, and with a consequent third step of engagement between a claw-shaped head of the upper clips and the claw-shaped edge of the profile, said claw-shaped edge remaining engaged against an elastic lamina of said upper clips; - the lower profile comprising at least one pair of tracks for the accommodation and sliding of the lower guiding rollers of the door wherein the lower profile provides for a first similar step of adjacent arrangement and insertion of its pivot into a transverse slot of the series of clips of the footing and then a second step of rotation of said lower profile until it touches the outer surface of the footing and with a consequent third step of engagement of its opposite claw-shaped end against a claw-shaped head of said series of lower clips whereby the upper clip is constituted by a flat body or base, on the lower part of which the rough stems (11a, 11b) are provided, said flat body having a raised part characterized in that said raised part being provided with two lateral claw-shaped ends or hooks with an intermediate tab which is lowered, with respect to the claw-shaped ends or hooks, so that since the upper clip is made of a sufficiently elastic material said tab becomes flexible as a consequence of any thrust applied from the side of the hooks or an edge (C') of the opening compartment of said piece of furniture. - the upper profile comprises at least one pair of longitudinal guides for the application of the pairs of pulleys for the sliding support of the door wherein the upper profile provides for a first step of adjacent arrangement and insertion of its claw-shaped edge in the series of clips of the top, then a second step of rotation of said upper profile until it touches the outer surface of the top, with simultaneous snap action for the insertion of its opposite edge against a series of heads or pins, of the system, and with a consequent third step of engagement between a claw-shaped head of the upper clips and the claw-shaped edge of the profile, said claw-shaped edge remaining engaged against an elastic lamina of said upper clips; - the lower profile comprising at least one pair of tracks for the accommodation and sliding of the lower guiding rollers of the door wherein the lower profile provides for a first similar step of adjacent arrangement and insertion of its pivot into a transverse slot of the series of clips of the footing and then a second step of rotation of said lower profile until it touches the outer surface of the footing and with a consequent third step of engagement of its opposite claw-shaped end against a claw-shaped head of said series of lower clips whereby the upper clip is constituted by a flat body or base, on the lower part of which the rough stems (11a, 11b) are provided, said flat body having a raised part characterized in that said raised part being provided with two lateral claw-shaped ends or hooks with an intermediate tab which is lowered, with respect to the claw-shaped ends or hooks, so that since the upper clip is made of a sufficiently elastic material said tab becomes flexible as a consequence of any thrust applied from the side of the hooks or an edge (C') of the opening compartment of said piece of furniture.