Endogenous gibberellins are plant hormones that are involved in plant developmental processes including the promotion of shoot elongation. Gibberellic levels can be suppressed by the use of synthetic growth regulators or genetic manipulation of constituents involved in signaling and biosynthetic pathway. Trinexapac-ethyl (TE) is a plant growth regulator that competitively inhibits 3-ß-hydroxylase responsible for hydroxylation of GA20 to physiologically active GA1 (Adams et al., 1992). Where it is registered it is widely used to reduce clipping yields and improve turf quality (Gardner and Wherley, 2005; Steinke and Stier, 2003). Repeated applications can be costly and may raise environmental concerns. Biotechnological manipulation of GA levels provides an alternative approach and has been successfully utilized in plant stature control. In plants bioactive GA1 and GA4 can be converted by 2β-hydroxylation catalyzed by GA2-oxidases (GA2ox) to inactive GA8 and GA34 (Hedden and Proebsting, 1999). Overexpression of GA2ox gene caused dwarf phenotype with darker green leaves in many economically important plants including rice (Sacamoto et al., 2001) and bahiagrass (Agharkar et al., 2007). The purpose of this study was to examine and compare the effect of TE application and runner been GA2ox gene overexpression on creeping bentgrass biomass accumulation and quality.