Peripheral nerve tissue engineering has great promise for growing replacement tissues to treat peripheral nerve injuries. To-date, the design of replacement tissues has focused on in vitro and in vivo experiments to characterise and test the impact of a vast range of materials, cells and other factors, with limited translation to human trials. Here we propose and discuss the use of in silico modelling as a complimentary approach to inform and accelerate the design of engineered replacement tissues.Mathematical modelling in nerve regeneration is a small research field; however, there is a rich literature in using mathematical modelling to describe a host of highly relevant underpinning mechanisms (such as neurite growth, chemical diffusion, angiogenesis) in different contexts. These models broadly fall into three categories: continuum (or averaged), discrete (or individual), and hybrid approaches which combine the two. The key features and potential of these frameworks is presented and a decision tree for matching the framework to a specific biological problem described. In order to be predictive, it is essential that mathematical models are benchmarked against experimental data. We present tools to efficiently fit models to these data (optimisation) and investigate the reliability of model predictions (sensitivity analysis). Finally, this work concludes with two demonstrative case studies on the use of mathematical modelling (one continuum, one discrete) to tackle biological and design questions in peripheral nerve injury repair.