Mirtazapine is a new antidepressant that can increase noradrenergic and serotonergic neurotransmission. It is also a postsynaptic antagonist of 5-HT₂ and 5-HT₃. In addition, it has only a weak affinity for 5-HT₁ receptors and has very weak muscarinic anticholinergic and histamine (H₁) antagonist properties. We report a case of hypertensive urgency that ensued after a patient took a single low dose of mirtazapine.