The theme of this graduate thesis is tensile properties of yarns and knits of different fineness and different raw composition. For exploring tensile properties, combed single yarns were used, there are of the same raw composition but different fineness (12,14 and 20 tex). From those yarns, single jersey knits were made with different raw material composition, cotton and mixture of cotton and elastane (6,8 and 13%). Tensile properties were tested and their resultes were compared considering the fineness and raw material composition. Yarn tensile properties were tested with dynamometer applying three methods, and tensile properties of knits were tested in dry and wet condition. The results of tested yarns showed that tensile properties are higher with increasing fineness. The results of the measurements enabled conclusion-making regarding the interdependence of the yarn fineness and tensile properties, as well as the influence of the application of different measurement methods to the final results. Regarding the knitted fabrics, it was shown that those are more stretchable in the direction of wales. The influence of the yarn fineness and the share of the elastic yarn in the knitting structure on the values of tensile properties in dry and wet condition is commented.