Most studies investigating human lumbar vertebral trabecular bone (HVTB) mechanical property–density relationships have presented results for the superior–inferior (SI), or “on-axis” direction. Equivalent, directly measured data from mechanical testing in the transverse (TR) direction are sparse and quantitative computed tomography (QCT) density-dependent variations in the anisotropy ratio of HVTB have not been adequately studied. The current study aimed to investigate the dependence of HVTB mechanical anisotropy ratio on QCT density by quantifying the empirical relationships between QCT-based apparent density of HVTB and its apparent compressive mechanical properties— elastic modulus (E_app), yield strength (σ_y), and yield strain (ε_y)—in the SI and TR directions for future clinical QCT-based continuum finite element modeling of HVTB. A total of 51 cylindrical cores (33 axial and 18 transverse) were extracted from four L1 human lumbar cadaveric vertebrae. Intact vertebrae were scanned in a clinical resolution computed tomography (CT) scanner prior to specimen extraction to obtain QCT density, ρ_CT. Additionally, physically measured apparent density, computed as ash weight over wet, bulk volume, ρ_app, showed significant correlation with ρ_CT [ρ_CT = 1.0568 × ρ_app, r = 0.86]. Specimens were compression tested at room temperature using the Zetos bone loading and bioreactor system. Apparent elastic modulus (E_app) and yield strength (σ_y) were linearly related to the ρ_CT in the axial direction [E_SI = 1493.8 × (ρ_CT), r = 0.77, p < 0.01;​ σ_Y,SI = 6.9 × (ρ_CT) − 0.13, r = 0.76, p < 0.01] while a power-law relation provided the best fit in the transverse direction [E_TR = 3349.1 × (ρ_CT)1.94, r = 0.89, p < 0.01;​ σ_Y,TR = 18.81 × (ρ_CT)1.83, r = 0.83, p < 0.01]. No significant correlation was found between ε_y and ρ_CT in either direction. E_app and σ_y in the axial direction were larger compared to the transverse direction by a factor of 3.2 and 2.3, respectively, on average. Furthermore, the degree of anisotropy decreased with increasing density. Comparatively, εy exhibited only a mild, but statistically significant anisotropy:​ transverse strains were larger than those in the axial direction by 30%, on average. Ability to map apparent mechanical properties in the transverse direction, in addition to the axial direction, from CT-based densitometric measures allows incorporation of transverse properties in finite element models based on clinical CT data, partially offsetting the inability of continuum models to accurately represent trabecular architectural variations.