There have been major advances in the understanding of the genetically determined neuropathies in recent years. The underlying genetic defects are now known for many of the demyelinating hereditary motor and sensory neuropathies, and linkage data are available for some of the axonal hereditary motor and sensory neuropathies. This has important implications for both diagnosis and genetic counselling in this group of conditions. The genetic defect in most cases of familial amyloid polyneuropathy is also now known. In the most common form of familial amyloid polyneuropathy (FAP), transthyretin-related FAP, liver transplantation has been established as the first definitive treatment for a hereditary neuropathy and should be considered especially in young adult patients. This review will concentrate on the advances in the molecular genetics of the hereditary motor and sensory neuropathies, the hereditary sensory and autonomic neuropathies and the familial amyloid polyneuropathies with particular emphasis on the difficulties in classifying the first group.