Milnacipran, one of the serotonin noradrenaline reuptake inhibitors (SNRIs) to which venlafaxine and duloxetine belong, is a new antidepressant that has recently become available in many countries. Despite the advances in pharmacotherapy, almost one third of patients with depressive illness respond inadequately to monotherapy with such an antidepressant. We herein describe five patients with major depression who responded partially, but not fully, to milnacipran alone and remarkably improved with an adjunct of risperidone. In addition, milnacipran plus risperidone was found to be a useful augmentation for treatment-refractory depression in 3 of the 5 patients. The minimum dose of risperidone, 0.5 or 1 mg/d, was efficacious. The time of response after addition of risperidone was within 4 d. Our experience suggests that an augmentation therapy of milnacipran plus risperidone is useful for treating patients with depression who only partially respond to various types of antidepressants and for treatment-refractory depression.