Poststroke depression (PSD) is one of the most frequent neuropsychiatric consequences of stroke. It has been shown to be associated with both impaired recovery and increased mortality. The purpose of this study is to investigate the prophylactic effect of milnacipran in PSD. Ninety-two patients were enrolled in the 12 months of this double-blind randomized placebo-controlled trial. The assessment was performed at baseline, and at the first, third, sixth, ninth and 12th month after enrollment. The definition of PSD was in accordance with the diagnostic criteria of major depressive episode based on the Diagnostic and Statistical Manual, fourth edition. Forty-six patients were randomized to the treatment group with milnacipran and another 46 patients to the placebo group. No significant differences were found between the two groups in terms of sex (P=0.83), age (P=0.08), marital status (P=0.66), occupation (P=0.22), educational level (P=0.29), and drug side-effects (P=0.73). The incidence of depression in the two groups was 2.22% and 15.22%, respectively. Milnacipran was proved to have a statistically significant advantage in preventing PSD (P<0.05). In conclusion, milnacipran could prevent the development of depression in the first year following a stroke and is safe to use without significant adverse effects in stroke patients.