Idiopathic spinal cord hernia (ISCH) is a rare cause of slowly progressive spinal cord dysfunction. It is readily diagnosed on magnetic resonance imaging of the spine. The neurological deficit related to ISCH is often reversible once surgical exploration and reduction of the hernia is achieved. We present the case of a 37 year-old lady with a ventral ISCH at the T4 level. There was a significant post-operative improvement in her myelopathy post-operatively. ISCH should be considered in the differential diagnosis of progressive spinal cord neurological deficit.