Ms. A was a 36-year-old nurse with a 10-year history of bipolar disorder that resulted in at least 15 hospitalizations, predominantly for episodes of psychotic mania. She was admitted to our closed ward for acute mania that was characterized by a euphoric mood, logorrhea, psychomotor agitation, insomnia, and religious delusions. Previous treatment with carbamazepine was stopped because of inefficacy. Ms. A started treatment with a loading dose of valproate, 1800 mg/day, and haloperidol, 6 mg/day. Topiramate was added to this standard regimen in a dose of 25 mg on day 1 and 50 mg on day 2. Ms. A improved rapidly, as shown by a decrease in her Young Mania Rating Scale score from 41 on day 1 to 13 on day 15. Sedation and extrapyramidal dyskinesia were recorded as side effects. On day 15, her topiramate therapy was discontinued, whereas her valproate and haloperidol therapy was continued with an unchanged dose. Ms. A experienced a serious relapse of her manic symptoms that resulted in a Young Mania Rating Scale score of 33 on day 19. Her topiramate therapy was restarted on day 19. Her Young Mania Rating Scale score decreased to 20 on day 23 and 11 on day 30. Her haloperidol treatment was discontinued on day 35 without any further recurrence of her manic or psychotic symptoms. Her plasma levels of valproate were 41.6 mg/liter on day 1, 64.5 mg/liter on day 13, 66.6 mg/liter on day 18, and 60.0 mg/liter on day 25. Her haloperidol plasma levels were reported to be below 2 mg/liter on days 3 and 13.