In order to understand the gene regulation during berry development and examine the effect of abscisic acid (ABA) on gene expression related to berry maturation, we evaluated the validity of four housekeeping genes, elongation factor 1-alpha (EF1-alpha), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), ubiquitin-conjugating enzyme (UBC), and 60S ribosomal protein L40-1 (VvUbiquitin1), as references by using 'Aki Queen' grapes with and without ABA treatment. The main contribution of this study is that a gene expression analysis using GAPDH as a reference gene will help to elucidate the berry development process and the physiological effects of ABA on berry maturation of 'Aki Queen' grapes.