The dual-core yarn structures, which make possible using of second core in the center of yarn has been the focus of attention for denim manufacturers in recent times. It is tried to gain different properties such as durability and flexibility to denim fabrics by using dual-core yarns. The aim of this study is to investigate the effects of twist, elastane, and wool draft ratio on the fatigue properties of dual core-spun yarns with two core materials as wool staple yarn and elastane filament. To know fatigue behavior of the yarns forming the fabric after repeated dynamic loads that is important to determine the permanent elongation that will occur in the fabric during its usage. Experimental results show that twist is a more effective parameter on elongation (before and after cyclic loading), tensile strength (before and after cyclic loading), dynamic modulus, and dynamic strain values. When core draft ratio parameters are observed, wool draft ratio is statistically significant on tensile strength after cyclic loading, elongation before cyclic loading, dynamic modulus. and dynamic strain values. Elastane draft ratio is statistically significant on the only dynamic modulus values.