Akathisia is a movement disorder characterized by an inner sense of restlessness and it needs attention because of the increased risk of suicidal behavior. Although akathisia may affect the trunk and arms, it predominantly affects the legs. Akathisia may occur exposure to antipsychotics and antidepressants. Mirtazapine is an antidepressant blocking presynapticα-2adrenergic receptors and 5-hydroxytryptamine (5-HT) 2A/2C, 5 HT 3 and histaminergic postsynaptic receptor. In this single case study, we aimed to present a case of akathisia which occurred after mirtazapine treatment. Case presentation: A fifty -two-years-old woman presented with a-one-month history of decreased sleep and appetite. She had been using antidepressant medication (Fluoxetine 40 mg / day) for five months due to depressive disorder. Mirtazapine 15 mg/day was added to the patient's treatment. Three hours after the first dosage she could not sit even for few minutes and complained of inner restlessness. She reported feeling anxious. Biochemical tests for metabolic/electrolyte parameters were within reference ranges. She had no neurological disease. Mirtazapine was removed and her symptoms resolved in one day. She consulted the department of internal medicine. Her physical examination was normal. Biochemical tests for metabolic/electrolyte parameters were within reference ranges. She had no neurological disease. Mirtazapine was removed and her symptoms resolved in one day. Akathisia is an important side effect because of related to a subjective experience of discomfort that can lead to suicidal behavior. This case illustrates the significant of being alert to any movement disorders in patients treated with mirtazapine.