Researchers investigated the influence of the lappet eye size of yarn guides on yarn quality. An experiment spun 37/1 carded and 30/1 carded yarns using four yarn guides with lappet eye sizes of 5, 3.8, 2.4, and 2.2 millimeters. Subsequent evaluation of yarn quality included measurements of count variation, yarn strength, strength variation, irregularities, evenness, hairiness, and end breaks at the ring spinning frame. The data showed that using a smaller lappet eye size resulted in fewer end breaks and produced yarns with less hairiness. If the yarn guide was smooth, the spindle speed could be increased without compromising yarn quality. The performance of the yarn guides depended on the ratio of the eye size to the yarn diameter, and the eyelet size could be optimized for the production of different yarn counts.