The orientation of fibers is known to play a very important role in determining the quality of the carded and drawn slivers as well as the quality of the ultimate yarns produced from those slivers. Also, the orientation of fibers is considered to be a very useful parameter for evaluating the effectiveness of the carding and drawing processes in aligning the fibers. In addition, the orientation of fibers is known to determine the length utilization of the fibers in the slivers. This article reports on the influence of carding and drawing processes on the orientation of fibers in the carded and drawn slivers. A series of carded and drawn slivers were prepared by using polyester staple fibers and making various changes in the carding and drawing processes and the orientation of fibers in the slivers was evaluated based on Lindsley's methodology in conjunction with a mathematical model of fiber orientation in slivers. It was observed that the increase in cylinder speed and the decrease in doffer speed resulted in more anisotropic fiber orientation distribution in the carded slivers and the degree of anisotropy was found to be more in the forward direction as compared to the backward direction of the carded slivers. The higher draft and doubling in the drawframe resulted in higher anisotropy in the orientation of fibers in the drawn slivers and the drawn slivers displayed more anisotropy in the backward direction as compared to the forward direction. The higher delivery speed of the drawframe resulted in higher anisotropy in fiber orientation in the drawn slivers and the drawn slivers exhibited more anisotropy in the backward direction as compared to the forward direction. The results of fiber orientation in the carded and drawn slivers obtained by using the mathematical model were compared to the fiber orientation parameters suggested by earlier researchers and a satisfactory correlation between them was observed.