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We report a case of essential segmental myoclonus a 10 year old girl who presented with continuing movement of both the shoulder girdle muscles for 6 months. The movements were exacerbated with the hands raised above the head or in the outstretched posture and were persisting during sleep. There was no abnormal palatal movement. Additionally there was a rhythmical clicking sound arising from the shoulders that could be felt and ausculated with the stethoscope. CT scan of brain and MRI of cervical spine were non-contributory, EMG showed muscle activates at about 50 per second in the shoulder girdle muscles. Cine-radiography of shoulder joints showed the head of humerus hitting against the spine of the scapula rhythmically. Spinal tap was non-contributory. The diagnosis or essential segmental myoclonus was entertained and the subject with fluoxetine, a selective serotonin reuptake inhibitor with remarkable response. The possible mechanism of action of agents modulating the serotonergic system in the brain for the management of myoclonus has been reviewed and their role suggested.