A cable ladder formed by two parallel side rails (1a; 1b; 1c) attached to one another by a plurality of parallel crosspieces (2A; 2B) spaced from one another, said plurality of crosspieces (2A; 2B) forming a discontinuous support surface for cables, said side rails (1a, 1b, 1c) and said crosspieces (2A; 2B) having the following features: - each of said crosspieces (2A; 2B) is an extruded profile made of a polymer material; - each of said side rails (1a; 1b; 1c) is an extruded profile made of a polymer material having, on its inner side facing the other side rail (1a; 1b; 1c), a channel (4a; 4b; 4c) receiving a corresponding end of said crosspiece (2A; 2B); - said channel (4a; 4b; 4c) of the side rails (1a, 1b, 1c) is demarcated by a lower rib (5a; 5b; 5c) and an upper rib (6a; 6b; 6c), said lower rib (5a; 5b; 5c) or said upper rib (6a; 6b; 6c) having at its end a projection (7a, 8a; 7b, 8b; 7c) extending towards the inside of said channel (4a; 4b; 4c), and a plurality of openings (9a; 9b; 9c) spaced from one another along the longitudinal direction of said side rails (1a; 1b; 1c) being formed in one (7a; 7b; 7c) of said projections; - each of the two ends of each of said crosspieces (2A; 2B) is formed such that it goes through said opening (9a; 9b; 9c) in the projection (8a; 7b; 7c) of the corresponding side rail (1a; 1b; 1c) and tightly fits in said channel (4a; 4b; 4c) of said side rail (1a; 1b; 1c), characterized in that: - said channel (4a; 4b; 4c) in the inner side of each side rail (1a; 1b; 1c) and the two ends of each of said crosspieces (2A; 2B) are formed such that each of said ends of the crosspiece (2A; 2B) fits and is snap-fitted into said channel (4a; 4b; 4c) of the corresponding side rail (1a; 1b; 1c); - each of said ends of said crosspieces (2A; 2B) is provided with at least one recess (10A, 11A; 10B) in which a corresponding portion of said channel (4a; 4b; 4c) of the side rail (1a; 1b; 1c) is snap-fitted; - and said lower rib (5a; 5b; 5c) of said side rails (1a; 1b; 1c) is bent back on itself along a bending line (19a; 19b; 19c), such that a final section of said lower rib (5a; 5b; 5c) is a free end section which experiences a slight lowering by elastic bending with respect to said bending line (19a; 19b; 19c) during introduction of the corresponding end of the crosspiece (2A; 2B) in said channel (4a; 4b; 4c) of the side rail, said slight lowering by elastic bending widening said channel (4a; 4b; 4c) of the side rail. - each of said crosspieces (2A; 2B) is an extruded profile made of a polymer material; - each of said side rails (1a; 1b; 1c) is an extruded profile made of a polymer material having, on its inner side facing the other side rail (1a; 1b; 1c), a channel (4a; 4b; 4c) receiving a corresponding end of said crosspiece (2A; 2B); - said channel (4a; 4b; 4c) of the side rails (1a, 1b, 1c) is demarcated by a lower rib (5a; 5b; 5c) and an upper rib (6a; 6b; 6c), said lower rib (5a; 5b; 5c) or said upper rib (6a; 6b; 6c) having at its end a projection (7a, 8a; 7b, 8b; 7c) extending towards the inside of said channel (4a; 4b; 4c), and a plurality of openings (9a; 9b; 9c) spaced from one another along the longitudinal direction of said side rails (1a; 1b; 1c) being formed in one (7a; 7b; 7c) of said projections; - each of the two ends of each of said crosspieces (2A; 2B) is formed such that it goes through said opening (9a; 9b; 9c) in the projection (8a; 7b; 7c) of the corresponding side rail (1a; 1b; 1c) and tightly fits in said channel (4a; 4b; 4c) of said side rail (1a; 1b; 1c), - said channel (4a; 4b; 4c) in the inner side of each side rail (1a; 1b; 1c) and the two ends of each of said crosspieces (2A; 2B) are formed such that each of said ends of the crosspiece (2A; 2B) fits and is snap-fitted into said channel (4a; 4b; 4c) of the corresponding side rail (1a; 1b; 1c); - each of said ends of said crosspieces (2A; 2B) is provided with at least one recess (10A, 11A; 10B) in which a corresponding portion of said channel (4a; 4b; 4c) of the side rail (1a; 1b; 1c) is snap-fitted; - and said lower rib (5a; 5b; 5c) of said side rails (1a; 1b; 1c) is bent back on itself along a bending line (19a; 19b; 19c), such that a final section of said lower rib (5a; 5b; 5c) is a free end section which experiences a slight lowering by elastic bending with respect to said bending line (19a; 19b; 19c) during introduction of the corresponding end of the crosspiece (2A; 2B) in said channel (4a; 4b; 4c) of the side rail, said slight lowering by elastic bending widening said channel (4a; 4b; 4c) of the side rail.