Abstract: A method and unit for forming, on a cartoning machine, a group having at least one row defined by a given number of products, whereby an orderly succession of products, traveling at a substantially constant first speed, is fed to conveyor traveling at a substantially constant second speed greater than the first speed; a leading product in the succession is braked on the conveyor until a portion of the succession corresponding to the row being formed moves onto the conveyor; and the leading product in the row is then released gradually to accelerate the row up to the second speed and detach the row from the rest of the succession.