Triphasic waves are seen in the electro-encephalogram of adult patients with toxic-metabolic encephalopathies of various origins. Levetiracetam is a broad spectrum anti-epileptic drug with renal elimination and no hepatic metabolism. We describe the case of encephalopathy with triphasic waves concomitant with levetiracetam accumulation in a patient with chronic renal failure. The condition was reversible after down-titration of levetiracetam with no change of the renal function. Other causes of metabolic encephalopathy were excluded. Moreover, this patient suffered from a probable cortical myoclonus that relapsed after cessation of the drug but was well controlled by a low dosage adapted to the renal failure. In cases of metabolic encephalopathy with triphasic waves in a patient with renal failure taking levetiracetam, it is important to exclude toxic accumulation of levetiracetam among other causes.