Modafinil is known as vigilance promoting drug used in hypersomnia, and an additive drug for major depression and bipolar depression’s residual symptoms. Modafinil is especially good at fatigue and awakeness. This case represents manic episode after modafinil usage in a patient with bipolar disorder, but on remission with valproate treatment. A 19 years old male patient that studies for college entrance exams lives with his family. He has got the diagnosis of bipolar disorder, two years ago and his treatment has been valproate 750 mg/day and olanzapine 10 mg/day for the last 8 months. He is on remission. He had three manic episodes until today, and he had no depressive or mixed episodes. Because he could not study concentrated and hypersomnia in daylight, modafinil 100 mg per day treatment is started. After only one dose, in the third day there is insomnia, in the fourth day, there is hyperactivity, nervousness, increased speech, grandiosity, aggressiveness to the family. Patient’s family applied to Psychiatric Hospitalization with manic episode without psychotic symptoms. Haloperidol 20 mg/day, biperidene 5 mg/day, valproate 1000 mg/day and olanzapine 10 mg /day treatment is started. Admitting valproate blood level is 58. In family history, there is a epileptic cousin, and two psychosis diagnosed cousins. In his biochemical tests, there a slightly elevated uric acid level but nothing else is other than normal. In the sixth day of hospitalization, upon family’s request, the patient discharged with serum valproate level of 65. Risperidone 2 mg/day, valproate 1000 mg/day and olanzapine 10 mg/day is prescribed. A week later, during the outpatient clinic control, it shows that the patient doesn’t take his risperidone, and he doesn’t want to take any medicine. His affect is euthymic, sleeps well, speech speed normal, aggressive behavior resolved. His follow-ups are continuing. In literature, modafinil is used as additive drug for resistant major depression, bipolar depression episodes. In this case, modafinil was added to treatment because of hypersomnia and distraction. In a research with bipolar disorder patients who took psychostimulant for ADHD or depression, psycho-stimulant related mania/hypomania ratio is 40%. By the way with no comorbid first axis diagnosis’ related to psychostimulants are more often than it. In this case, there is no other first axis diagnosis too. In a research with bipolar disorder patients, who is on remission with hypersomnia, it was shown that modafinil was efficacious on patients with not manifested depressions. The paper says that modafinil was more tolerable and less episodic than the other stimulants. In literature, there are researches that advice modafinil as an additive treatment in bipolar disorder’s depressive episodes, but also it can cause manic shifts too. There are case reports, which describes psychosis, manic shifts induced by modafinil too. In this case, it is remarkable that, even with valproate treatment, on a remission bipolar disorder patient, modafinil can induce manic shift. This case report wants to get attention to modafinil treatment follow-ups, especially for manic shifts.