This study was performed to determine the effects of structural characteristics of selected wool fabrics on thermal transport properties. 52 wool fabrics, including 18 plain woven fabrics and 34 twill and satin woven fabrics were used as samples. They were woven with various weft densities for this study. The followings were obtained from the results: The main factors affecting keeping warmth ratio were thickness and bulk density. The keeping warmth ratio of samples increased with increasing thickness and decreasing bulk density of samples. And keeping warmth ratios of samples with finer yarns were higher than those of samples with coarse yarns, specially for plain and twill woven samples. The increase of keeping warmth ratio was great in case of plain woven fabrics, while there was no increase of keeping warmth ratio in case of twill and satin woven fabrics. The results showed that the increase of keeping warmth ratio with thickness increase was least in case of satin woven fabrics.