The employment of passive shimming techniques using dielectric padding can improve the homogeneity of B1+ fields and increase signal-noise-ratio (SNR) in breast MRI at 3 tesla. Numerical simulations were conducted in xFDTD utilizing spatially constant and tailored permittivity approaches. High dielectric pads of varying permittivity resulted in a 50-500% increase in SNR throughout the breast, as well as significant improvements to transmit efficiency and a decrease in left-right asymmetry across the breast.