A cost-effective estimation of wood quality of hardwood green logs is needed. The purposes of this study were to investigate and compare two nondestructive acoustic methods to predict the wood quality of green logs from a poplar I-72 (Populus ×euramericana cv. I-72/58 “San Martino”) plantation. After log measurements, small clear wood specimens were cut and air dried to 12 percent moisture content. The static bending modulus of elasticity (MOE) of small clear wood specimens was about 15 and 20 percent greater than the dynamic MOE of green logs based on resonance vibration (E_fr) and stress wave (E_sw). However, good correlations (R) between E_fr and E_sw of logs and bending MOE of 0.806 and 0.848 (P <0.001), respectively, were observed. Significant correlations were also found between the E_fr and E_sw of logs and the modulus of rupture and compressive strength parallel to grain (σ_c) of small clear wood specimens (P < 0.001). The results indicate that both acoustic techniques were effective predictors of wood quality, although the stress wave method was found to be more accurate and reliable than the resonance vibration method. The longitudinal changes of strength properties with tree height could be tracked by these two methods.