Epidural lipomatosis has been implicated as a cause or contributor of symptomatic lumbar spinal stenosis. Symptomatic spinal epidural lipomatosis (SEL) of the lumbar spine is a rare disease, often associated with steroid overload. Idiopathic lipomatosis is even much less frequent. Signs and symptoms depend upon the level and degree of nerve root compression. Diagnosis is best based on MRI. Weight reduction can be curative, however, after failure of medical treatment or in severe cases surgical decompression should be performed. A 70-year-old man with both lower limb severe paresthesia and radicular symptoms unrelieved with conservative treatments such as medications and physical therapy was treated by surgical decompression. Obesity, endocrinopathic disease, and chronic steroid therapy were excluded. Interlaminar fenestration, lateral recess decompression and fat debulking were applied at all levels through the L2-S1. After surgery there was a gradual improvement in symptoms. We report a rare case of idiopathic SEL which has shown entire evolvement of lumbar spine with specific increase of radiological and clinical severity from L2-3 to L5-S1 in a non-obese patient.