The basic intention of the presented research is to analyse the permeability properties of woven fabrics containing
two-ply fancy yarns in the weft direction. Within the framework of presented research, two-ply fancy yarns were
analysed. Because of their structure, they are classified as fancy yarns with structural effects. The first analysed two-ply
fancy yarn is made of the mixture of 81% cotton and 19% viscose. The second is made of the mixture of 67% viscose
and 33% flax. For the purpose of the presented research, woven fabrics containing two-ply fancy yarn were made in
three different densities in weft (10 threads per cm, 13 threads per cm, and 16 threads per cm) in the twill weave T 1/3 Z.
The theoretical part includes the historical development of the production of the fancy yarns, a detailed discussion of the
ring production processes, the types and the structure of the fancy yarns, their use, and the global and European market
of the fancy yarns. The experimental part consists of three parts. In the first part, the structural properties of the analysed
fancy yarns were researched (the fineness of the fancy yarn, the frequency of repeating the effects per one meter of the
yarn, the direction of twisting the fancy yarn, the number of the twists of the basic and the effective part, the diameter of
the fibers, the diameter of the basic and the effective part, the fineness of individual components, the direction of the
twist of individual components, and the percentage of the inside twist of individual components). In the second part,
constructional properties of the analysed woven fabrics with the fancy yarn in the weft were researched (mass,
thickness, the density of the warp and weft threads, and openness of the surface). In the third part, permeability
properties of the analysed woven fabrics with the fancy yarn in the weft were researched where greater attention was
paid to air permeability and water vapour permeability. The results of the research showed that the samples with the first
two-ply fancy yarn in the weft (81% cotton and 19% viscose) have greater air permeability and water vapour
permeability. Meanwhile, the samples with the second two-ply fancy yarn in the weft (67% viscose and 33% flax) have
lesser abrasion resistance and poorer dimensional stability while being washed.