After the use of bromide as the first antiepileptic drug in 1857, conventional antiepileptic drugs were introduced and stabilized through clinical experiences. Since the 1990's, new antiepileptic drugs have been developed in the base of biochemical mechanism. Thus the variety of antiepileptic drugs is available nowadays. There are relatively enough understandings about the adverse effects of the conventional antiepileptic drugs. On the other hand, even though it is generally accepted that new antiepileptic drugs may have less adverse effects than conventional antiepileptic drugs, the clinical experiences about the new antiepileptic drugs are not enough to comprehend adverse effects. Adverse effects are one of the most important aspects to be considered when selecting antiepileptic drugs in each individual patient. Its importance is more emphasized by the fact that adverse effects may increase the cost of antiepileptic therapy. Thus physicians should be familiar with the common and characteristic adverse effects of antiepileptic drugs. Even among the patients with a same epileptic syndrome, the selection of antiepileptic drugs should be tailored according to the individual susceptibility to adverse effects. As the knowledge about adverse effects of antiepileptic drugs is accumulated and the patients' interests about health are increased, the information about adverse effects of antiepileptic drugs is becoming more and more important.