In the Netherlands, approximately 100,000-400,000 people suffer from polyneuropathy. Polyneuropathy has many different causes, diabetes mellitus being the most frequent one. The practice guideline 'Polyneuropathy' describes the diagnostic procedure in patients with signs or symptoms of polyneuropathy that need to be followed in order to identify the cause of the condition. After history taking and neurological examination, the diagnosis ofpolyneuropathy can be made with a high degree of accuracy. Electrophysiological investigation may be of help, especially in classifying an axonal or demyelinating form of polyneuropathy. This subclassification is important because it helps to identify possibly treatable forms ofpolyneuropathy. Most polyneuropathies follow a slowly progressive course. If the course of the polyneuropathy deviates from what is to be expected, neurological consultation and additional diagnostic tests should be performed. A diagnostic flowchart has been designed to serve as a practical guide to an effective and rapid procedure to diagnose the cause of a polyneuropathy. Amitryptiline and carbamazepine have been proven to be effective and are the drugs of first-choice, except in HIV-related polyneuropathy, in which case only lamotrigine has been proven effective.