It is well known that the fibers and the slivers to be assembled into roving or yarn need to meet certain criteria in terms of cohesion and drafting characteristics for trouble-free performance in spinning and for optimum yarn evenness. The cohesive force is defined as the force required to overcome fiber cohesion when the strand is being reduced in linear density and affects the drafting force. Experience has shown that the drafting force declines with increasing length of draft zone, and with increasing draft, but individual tests need to be performed to determine the extent and whether this is the case for all types of fibers. In this study the effects of drafting conditions such as draft ratio, roller speed, roller gauge, and the pressure of roller on the cohesive force of cotton, junlon, and modal roving were investigated. It was found that cohesive force declined with increasing draft ratio and likewise with increasing drafting zone length, but increased with increasing roller speed. For the raw materials investigated in this paper, cohesive force exhibited a decline with increasing draft ratio. And it was shown that the cohesive force of roving was also dependent on the roving twist.