This study investigates the effect of the distribution of dyes in indigo-dyed denims on subsequent washdown characteristics. Two commercial samples of indigo dyed denims, having the same initial depth of shade (L=2.40, b=-7.2) are desized and washed down with cellulase enzymes to produce fabrics having significantly different shade depths (fabric F1; L=29.4, b=-14.2, fabric F2: L=24.1, b=-13.8, respectively). Examination of yarn penetration of indigo dyes prior to washing through image analysis showed that the degree of ring-dyeing is a major source of shade depth variation after washing. The more ring-dyed denim (sampled F1) with less dye content is washed down in a shorter period of time, resulting in less strength reduction of denim fabrics. Difference in the degree of ring dyeing is observed to be approximately one layer of Ne=8 cotton yarns. Indigo-dyed denims before and after desizing and washing are evaluated using color parameters such as L and -b(blueness) values. In color measurements of commercial indigo denims, a problem caused by large surface reflectance due to the presence of sized is discussed.