This chapter provides a comprehensive and comprehensible review of the major antiepileptic drugs (AEDs). Patients often hear their physician talk about 'drug levels'. A drug's effectiveness is determined by its ability to control seizures. Unfortunately, the drug, by its actions on the body or brain, may cause unwanted side effects as well. There are several types of side effects, but the most common are dose-related side effects. Dose-related side effects may include fatigue, dizziness, lack of coordination, or double vision. Diet and exercise can help, and the weight usually returns to baseline if the drug is discontinued. Phenytoin, in particular, can cause some cosmetic side effects that are troublesome to women. Several new AEDs have recently been approved by the Food and Drug Administration. These include gabapentin, lamotrigine, topiramate, tiagabine, levetiracetam, and oxcarbazepine. A newer technique recently approved for epilepsy treatment is the vagal nerve stimulator.