A rotary conveyor with suction and change of pitch for transferring containers, comprising: a rotary platform rotating about a rotation axis; a plurality of guiding elements fixed to said rotary platform; a plurality of grooves formed in the rotary platform, each in a position parallel to one of said guiding elements, where the guiding elements and said grooves are uniformly distributed around said rotation axis and extend from a peripheral region to a central region of the rotary platform; a stationary closed-loop cam located below the rotary platform, said closed-loop cam defining a path not centered with respect to the rotation axis; a plurality of runners, each being slidingly coupled to one of said guiding elements; a cam follower assembled on each runner, said cam follower being inserted through one of said grooves and coupled to the closed-loop cam, whereby each runner performs a back and forth movement along the corresponding guiding element during one rotation of the rotary platform; and a plurality of retaining elements, each fixed to one of said runners and provided with a suction port suitable for retaining a container, each suction port being in communication with a suction chamber along a portion of each rotation of the rotary platform; characterized in that: said suction chamber is supported in a stationary position above the rotary platform and has a perforated side wall parallel and adjacent to a portion of said path not centered with respect to the rotation axis defined by the closed-loop cam, air being suctioned from the outside into the suction chamber through said perforated side wall; and each of the retaining elements has a suction outlet in communication with the suction port, said suction outlet moving in a path facing and adjacent to the perforated side wall of the suction chamber during a part of each rotation of the rotary platform. a rotary platform rotating about a rotation axis; a plurality of guiding elements fixed to said rotary platform; a plurality of grooves formed in the rotary platform, each in a position parallel to one of said guiding elements, where the guiding elements and said grooves are uniformly distributed around said rotation axis and extend from a peripheral region to a central region of the rotary platform; a stationary closed-loop cam located below the rotary platform, said closed-loop cam defining a path not centered with respect to the rotation axis; a plurality of runners, each being slidingly coupled to one of said guiding elements; a cam follower assembled on each runner, said cam follower being inserted through one of said grooves and coupled to the closed-loop cam, whereby each runner performs a back and forth movement along the corresponding guiding element during one rotation of the rotary platform; and a plurality of retaining elements, each fixed to one of said runners and provided with a suction port suitable for retaining a container, each suction port being in communication with a suction chamber along a portion of each rotation of the rotary platform; said suction chamber is supported in a stationary position above the rotary platform and has a perforated side wall parallel and adjacent to a portion of said path not centered with respect to the rotation axis defined by the closed-loop cam, air being suctioned from the outside into the suction chamber through said perforated side wall; and each of the retaining elements has a suction outlet in communication with the suction port, said suction outlet moving in a path facing and adjacent to the perforated side wall of the suction chamber during a part of each rotation of the rotary platform.