Properties of ion channels are affected by the background of the cells in which they are expressed. Thus, it is important for investigators interested in neuronal function to study these proteins in post-mitotic neurons. However, post-mitotic neurons, and many cell lines, are difficult to transfect by standard methods. Here we provide detailed protocols for two different procedures, biolistic and electroporation, which have been used to transfect peripheral sensory neurons from mice or rats with expression constructs of voltage-gated sodium channels. Neurons can be prepared, transfected and currents recorded within 48 h. Using these methods, primary sensory neurons can be transfected with an efficiency of 5-20%, which has permitted studying biophysical properties of sodium channels and their naturally occurring mutants in a native neuronal cell background. Although we have used sodium channels for the examples that we show here, these methods can also be used to study other types of molecules.