In order to investigate the effects of drafting parameters and roving specifications on the drafting forces in break draft zone of the roller drafting system, drafting forces were measured. It was known that, by the discussion of the experimental results, the maximum values of drafting forces were occurred at a certain draft ratio, but these values were increased and shifted to the higher draft ratio as the twists of roving were increased. The draft ratios at maximum drafting forces may be considered to be determined by break draft ratio.