This study is being conducted to compare the efficacy and safety of LAMICTAL (lamotrigine) extended-release with placebo in the treatment of partial seizures. LAMICTAL extended-release is an investigational drug. Placebo tablets look like LAMICTAL extended-release tablets but do not contain active medication. In this study, LAMICTAL extended-release or placebo tablets will be added to current seizure treatments.

Inclusion criteria:

• Diagnosis of epilepsy with partial seizures for more than 24 weeks.
• Must experience at least 8 partial seizures during an 8-week Baseline Phase.
• Must currently be receiving treatment with a stable regimen of one or two antiepileptic drugs for at least four weeks.
• Patient or parent/caregiver must be willing and able to maintain a written daily seizure diary.

Exclusion criteria:

• Previous treatment with lamotrigine.
• Exhibits any primary generalized seizures.
• Receiving treatment with felbamate or currently following the ketogenic diet.
• Pregnant, breastfeeding, or planning to become pregnant.

Patient-level data for this study will be made available through www.clinicalstudydatarequest.com following the timelines and process described on this site.