Peripheral neuropathy is a common neurological disorder, with high prevalence especially in the aged population. The general evaluative approach is to first identify the type of peripheral neuropathy prior to investigating for a possible underlying etiology, which is an increasingly important endeavor, as many causes of peripheral neuropathy are now recognized as treatable. To this end, laboratory testing plays an important adjunctive role to a detailed history and examination. This review will discuss possible diagnostic laboratory testing pathways for different types of peripheral neuropathy, with the goal of minimizing costs and false-positive results while maximizing the likelihood of identifying a potentially reversible etiology.