Softeners are commonly applied during manufacture and care of garments, mostly for improved feel and odor they offer. However, they alter some of the properties of the textile materials on which they are applied. To achieve the thermal regulation of the human body, air and water vapor permeability properties of the fabrics are very important parameters. From point of this view, it was the aim of the study to investigate the effects of softener on air and water vapor permeabilities of the fabrics. For a deeply investigation; cationic, nonionic and silicone were selected as softener types, and they were applied at various concentration levels (0, 1, 2, 3 %) on bleached or bleached&dyed fabrics which were knitted by using ring or open-end yarns. To evaluate the results ANOVA and t-test analyzes were used. According to the results, fabrics made from open-end yarn showed better air and water vapor permeability. In addition to that, additional wet process was shown to change the permeability properties of knitted fabrics. Also, treatment with softener affected permeability properties negatively, but the effects of concentrations of the softeners studied were more significant on air permeability than those on water vapor permeability. Furthermore, among the softeners studied, non-ionic softener performed superior to cationic and silicone softeners in terms of air and water vapor permeability.