The significance of ewe genotype and its interactions with sire effects were examined for Merino fleece traits recorded between post weaning and adult stages of progeny at the Macquarie site of the Merino Lifetime Productivity project. Across post weaning, hogget and 3 adult expressions, ewe bloodline effects significantly influenced fleece traits, particularly fleece weight and fibre diameter. Sire X ewe genotype interactions on fleece traits across ages were generally unimportant, accounting for small amounts of the phenotypic variance (less than 1%). Correlations between sire progeny performances were generally greater than 0.70. These results support the methods used routinely to account for these effects in MERINOSELECT genetic evaluations.