U.S.-produced cotton is among the cleanest available in the world; however, pieces of sheet plastic are found occasionally in cotton bales produced in the U.S. Standard cotton ginning equipment is not efficient in removing plastic contaminating seed cotton. The purpose of this work was to examine how selected operating conditions affect the sheet-plastic removal efficiency and fiber loss of one type of gin cleaning machine, the cylinder cleaner. In the first part, two sources of plastic were each tested in a central composite design, varying air flow rate through the machine, seed cotton processing rate, and size of plastic contaminant. In the second part, only one plastic source was used, but two cotton cultivars were tested in a central composite design. An additional response surface variable, cylinder rotation speed, was evaluated. Plastic removal increased linearly with increasing air flow rate and decreasing size of the plastic pieces. The effect of seed cotton processing rate on plastic removal was less significant than the effect of air flow rate or plastic size in the first part and was not statistically significant in the second part. The plastic from shopping bag material was removed more effectively than module wrap material. More plastic was removed at lower cylinder rotation speeds. Fiber loss increased with higher air flow rates or cylinder rotation speeds and lower seed cotton processing rates. Lower cylinder rotation speeds increased plastic removal and decreased fiber loss; selecting the optimum air flow rate was a compromise between plastic removal and fiber loss.