Efficacy of magnetic stimulation of the central or peripheral nervous system depends on the spatial and temporal distribution of the induced electric field generated by the magnetic coil. Therefore, accurate estimation of the induced electric field is crucial to the design and optimization of magnetic coils, particularly as the coil dimensions are reduced. In this work, we developed a numerical model of a multifascicular sciatic nerve to study the effect of tissue heterogeneity on the induced electric field. Using a multi-resolution electric field solver, we can resolve feature sizes as small as 1μm, allowing inclusion of the nerve membrane and the myelination layer. Preliminary results indicate that fascicle distribution and axons' proximity to each other significantly affect the magnitude and distribution of the induced electric field as compared to traditional homogeneous tissue models for field simulation.