Delirium is described as a sudden onset organic brain syndrome characterized by a disturbance of consciousness with reduced ability to focus, sustain, or shift attention resulted from physical or pathophysiological reasons. The important causes of delirium in the central system diseases, pharmacological and non-toxic materials, or poisoning or starvation. Here, we report a case of 9 years old children who developed escitalopram-induced delirium. 9 year-old girl was admitted to emergency with difficulty in breathing, inability to remember her family and delusion because of received three escitalopram 10 mg pills accidentallly. On psychiatric examination, she had disorientation, hallucinations and inappropriate responses to the questions. Her physical and neurological examinations were unremarkable. Laboratory results were normal. Therefore, her diagnosed was considered as delirium and patient improved with haloperidol. Selective Serotonin Reuptake Inhibitor (SSRI), group of antidepressants, increases the rate of pre-and postsynaptic via serotonin transporter inhibition. It was suggested that delirium may result from interaction between monoaminergic and cholinergic system. Excess or deficiency of serotonin may be associated with cholinergic deficiency and predispose to delirium.