Adjunctive use of methylphenidate, a central stimulant, has been considered as a potential therapeutic choice for patients with refractory unipolar depression, geriatric depression, bipolar depression, and depression secondary to a medical illness. We present a case of psychotic unipolar depression in which the patient responded significantly to the adjunctive use of methylphenidate. A 45-year-old woman had melancholic depressive symptoms and mood incongruent psychotic features during her second episode of unipolar depression. She attempted suicide by hanging herself and was forcibly hospitalized. She was initially treated with venlafaxine (262.5 mg/d), olanzapine (20 mg/d), and benzodiazepines. However, she responded unsatisfactorily to the combination treatment. Because her family refused electroconvulsive treatment, we added methylphenidate to her medications for adjunctive use. The dose of methylphenidate was started at a dose of 5 mg/d. It was not until the patient received 30 mg/d of methylphenidate that her persistent psychosis and severe depression were substantially improved. She tolerated her medications well and did not report any side effects. She was discharged in a stable condition 2 weeks after the adjunctive use of methylphenidate. The patient's methylphenidate was gradually tapered and finally discontinued. To date, she remains well and is regularly followed up at our outpatient clinic. Our case suggests that adjunctive use of methylphenidate can be a therapeutic option in treating some patients with psychotic unipolar depression who do not adequately respond to the combination treatment of an antidepressant and an atypical antipsychotic. Further controlled studies are warranted to verify this.