The neurotoxic capacity of a compound will depend largely on the route of entry into the body, the pattern and duration of exposure, the metabolism of the agent in question, and whether it is bioaccumulative or excreted. In the nervous system there are mainly four targets: the cell body, the axon, the myelinating cell and the neurotransmitter system. We propose in this book to be reference guides in the identification of the most frequent and known agents that cause occupational peripheral polyneuropathies, with the intention of guiding the occupational physician in the way of defining whether it corresponds to an occupational disease or a disease of common origin.