A method for producing a bag from a tube including transverse lines of perforations delimiting tabs of the future bag, a rear tab of a first bag being opposite a front tab of the second bag following the first. A first step involves separating the first and second bags; a second step involves separating a piece of waste remaining on one of the bags between the two tabs. The first and second steps are carried out between a first pair of separation cylinders and a second pair of cylinders, the piece of waste being clamped between the cylinders of the first pair during the first step in order to be held on the second bag, then clamped and torn off by the second pair during the second step.