This open, clinical study describes the use of lamotrigine in 200 adults and children with drug resistant epilepsy. Lamotrigine was used largely as add-on therapy and outcome was assessed by the patients, parents and carers and the physician in terms of reduction of seizure frequency, drug side-effects and improvement in quality of life. Of the 200 patients, 70 (35%) were rendered seizure free. Lamotrigine was especially helpful in resistant primary generalized epilepsy, complex partial seizures, mixed seizures subsequent to brain damage, Lennox-Gastaut syndrome and in complex partial seizures which secondarily generalized. Fifty-three patients ceased lamotrigine; 30 due to lack of effect, and 13 due to side-effects. Lamotrigine is a very useful antiepileptic medication of a "broad spectrum' nature being effective in primary generalized epilepsy and partial seizures as add-on therapy. The side-effect profile is good with most side-effects being avoidable.