There is still a need for a new analgesic devoid of the side effects presented by opioids or non-steroidal anti-inflammatory drugs, for the treatment of some acute and chronic pain conditions. Lamotrigine (Lamictal1, 10-100 mg/kg), a new anticonvulsant, showed analgesic effects in the acute model of prostaglandin E2 (PGE2)-induced hyperalgesia when given orally before or after the subplantar injection of PGE2 in the rat. It also inhibited the development of sustained hyperalgesia induced by multiple subplantar injections of PGE2 when administered orally prior to the PGE2 injections. Furthermore, lamotrigine induced analgesia in the model of chronic hyperalgesia in streptozotocin-induced diabetic rats. The effects of carbamazepine and phenytoin are compared to the effects of lamotrigine in this model. The results suggest that lamotrigine could be used in pain conditions where neuronal sensitization may be present and possibly also where it could inhibit the development of this sensitization.