Abstract: Growth performance as well as marbling is the main breeding objectives in Japanese Black cattle, the major beef breed in Japan. The researchers have recently reported that a Single Nucleotide Polymorphism (SNP), referred to as g.231054C>T in promoter region of the Titin (TTN) gene was associated with marbling in Japanese Black beef cattle with the T allele being associated with a high level of marbling. The TTN is known to be involved in myofibrillogenesis and has been previously shown to be located within genomic region of a quantitative trait locus for rib eye area. Thus, the TTN was considered as a positional functional candidate for the gene responsible for growth performance. In this study, the researchers analyzed the effect of the TTN g.231054C>T SNP genotypes on the growth-related carcass traits in Japanese Black beef cattle. The SNP was marginally associated with rib eye area in two experiments using 101 sires (p = 0.067) and 820 paternal half-sib progeny steers from 3 sires homozygous for C allele at the g.231054C>T (p = 0.090) in Japanese Black beef cattle. These findings suggest possible effect of the g.231054C>T on the growth-related trait in Japanese Black beef cattle. The TTN SNP polymorphism may be useful for effective marker-assisted selection to increase the beef productivity in Japanese Black beef cattle.