The chronological profile of cleaved eggs proportion (CEP) and the mean time to first embryonic cleavage (TFC) were determined in eggs batches from individual rainbow trout inseminated either with the sperm of individual males or with a pool of sperm. Both criteria exhibited a noticeable inter-individual variability resulting from a predominant maternal effect and a weaker paternal effect. TFC was delayed by post-ovulatory oocyte ageing, and positively correlated with malformation rate at yolk-sac resorption.