Observations made with lamotrigine add-on therapy with venlafaxine in this case give clues for some aspects of its use in adolescent-onset bipolar 11 disorder. An 18-year-old adolescent boy with a 3-year history of bipolar 11 disorder had experienced 2 episodes of hypomania and 4 episodes of major depression. He had been depressed for the last 3 months and had taken olanzapine 5 mg daily for over 6 weeks as mood stabilizer but was still depressed at referral. Other aspects of the patient history included anhedonia, psychomotor retardation, poor concentration, a feeling of hopelessness, hypersonmia, overeating, weight gain, low energy and a refusal to attend school. Parents reported that his symptoms had recently become more severe. His medicine was replaced by venlafaxine, which has a more rapid onset of action and is often used in bipolar depression, especially in patients with atypical depression. Since the clinical response at 6 weeks was only partial, lamotrigine was added to this regimen. The patient responded to lamotrigine after 3 weeks of treatment while on a dose of 50 mg/day. After 6 weeks of treatment, whilst on a dose of 75 mg/day, his symptoms remitted completely with no evidence of any adverse effects. At the time of publication of this article, the patient had remained euthymic for a total of 8 months. The present report shows that lamotrigine add-on therapy with venlafaxine facilitated clinical remission and that this combination is well tolerated.