Dual-core yarn, which is a new type of core-spun yarn, has been developed to improve the core-spun yarn properties. The yarn generally comprises elastic/semi-elastic core filaments, and both filaments are covered by sheath fibres. Dual-core yarns have attracted the interest of textile producers and researchers due to the possibility to enhance various functional properties of fabrics. The present study aimed to analyze the effect of various production parameters on dualcore yarn and fabric properties. In the study, X55 and PBT core filaments were used with Spandex filament as a core material of dual-core yarn, while viscose, cotton and cotton/Tencel fibres were chosen as a sheath fibre for covering the core filaments in the yarn centre. Dual-core yarns were produced with three different yarn fineness levels and some properties of the yarn (irregularity, imperfections, hairiness, tenacity and breaking elongation) and of the fabric (tensile properties and bending rigidity) were investigated. The results showed that all production variables have considerable influence on dual-core yarn and fabric properties, and the strength of each parameter changes depending on the yarn and fabric properties.