In this paper, the impact of short fiber content, yarn count and yarn delivery speed on the structure and properties of fine count cotton vortex yarns were investigated. The factors affecting the fine count yarn spinning on a vortex spinning system were determined on the basis of yarn structure and properties by using the linear regression technique. Moreover, the spinning limits of combed cotton vortex spun yarns were investigated. The results of the experiments revealed that the short fiber content in the cotton sliver is an important parameter in spinning fine count vortex spun yarns. The lower short fiber content in the sliver allows finer counts to be spun in the vortex spinning system. It was also observed that yarn delivery speed influences the yarn structure, and hence the yarn properties significantly, since it determines the residence time of the fibers in the yarn formation zone, and also affects the fiber control due to the air flow caused by the surface speed of the delivery rollers. In addition, the structure and properties of vortex spun yarns change significantly with regard to yarn count.