The objective of the study was to determine how maternal age influences the transcriptome of the dominant follicle during the preovulatory period. We tested the hypotheses that delayed ovulation in aged cows is associated with 1) altered gene expression of granulosa cells of preovulatory follicles (24 h after LH treatment) and 2) decreased synthesis of progesterone by granulosa cells of the preovulatory follicle. Granulosa cells of preovulatory follicles obtained 24 h after LH treatment from aged Hereford cows (19.0 ±2.5 years; n=3) were compared to those from young cows (9.0 ± 0.6 years; n=3) using bovine specific microarrays (EmbryoGENE-EMBV3; GPL13226). Results were confirmed by RT-qPCR. A total of 1340 genes or gene isoforms were expressed differentially (≥2-fold change; p ≤ 0.05) in aged cows vs. young cows (daughters of aged cows). In conclusion, transcriptome analysis of granulosa cells from aged cows revealed a delayed or suboptimal response to the preovulatory LH stimulus, represented by delayed cellular differentiation, luteinization and progesterone synthesis. Granulosa cells of the dominant preovulatory follicle 24 h after LH treatment were compared between aged vs.young cows. Three biological replicates (each composed of one aged and one young cow). 3 Three technical replicate (dye swap). One biological or technical replicate per array.