In recent years, it is observed that the conventional methods in the production process are insufficient with parallel to the development of technology. It is an unavoidable solution to produce high-value-added products in order to increase Turkey's export share. One of the solutions in yarn production is to manufacture functional yarns by using different raw materials. In this study, dual core-spun yarns were produced by a modified ring spinning system that allows the feeding of the two different core materials simultaneously. Within the scope of the study, dual core-spun yarns with two different yarn count (Ne 12/1 and 18/1) were produced using three different sheath fibers (100% cotton, 60/40% cotton/polyester, and 100% polyester) and core materials (PET/PTT bicomponent filament + elastane, Polybutylene Terephthalate (PBT)+elastane, and Polyethylene Terephthalate (PET)+elastane) at the same production conditions. In order to determine the effects of yarn count, sheath fiber and core material on yarn tenacity and elongation, yarn unevenness, imperfection and hairiness properties, analysis of variance (ANOVA) was conducted using SPSS package program at 95% confidence interval. © 2019 Chamber of Textile Engineers.