The repeatabilities on Yolk percentage and yolk to albumen (Y:A) ratio of the eggs produced consecutively were investigated. The differences between two yolk lines in major egg characteristics were also evaluated. The investigations using one hundred ISA-Brown layers were conducted at 29 wk, 33 wk, 38 wk, and 43 wk of age. At the initiated age (29 wk of age) of the experiments, the birds producing eggs with lower or higher Y:A ratio than the overall mean Y:A ratio were classified as Low Yolk Line (LYL) or High Yolk Line (HYL), respectively. Overall, the eggs of LYL were significantly (P<0.05) lighter in yolk weight and lower in yolk percentage for the whole egg weight and Y:A ratio, but heavier in egg weight, albumen weight, and shell weight than those of HYL. The overall mean correlations among the three consecutive laying days in Y:A ratio showed highly significant (P<0.001) in both lines. At four different ages, the mean phenotypic correlation coefficients (r$_{p}$) among the three consecutive laying days in Y:A ratio also had very high significant(P<0.01 ~ 0.001) positive values. The egg weight was more closely associated with albumen weight than with yolk weight in both yolk lines.s.