Introduction: Antidepressant drugs are used in the treatment of pain as an adjuvant or alone. It has been shown that antidepressant drugs have analgesic effects in various diseases (diabetic neuropathy, low back pain, cancer pain etc.) Sertraline is a potent serotonin re-uptake inhibitor. Some antidepressant drugs inhibited both of the reuptake of serotonin and of noradrenaline. These drugs are called serotonin-noradrenaline re-uptake inhibitors (SNRIs). Milnacipran is a serotonin-noradrenaline re-uptake inhibitor. We have studied the analgesic effects of sertraline and milnacipran after acute and chronic application in tail-flick test in mice.