The authors present a case of methyprylon (No ludar) overdose treated with extracorporeal hemodialysis. Dramatic clinical improvement was shown during the 9 hour period of dialysis with serum methyprylon levels decreasing from 4 to 0.4 mg/ml. Less than 10% of the ingested methyprylon was recovered from the bath. Dialysis of the toxic metabolites of the drug may explain the rapid clinical improvement observed. (NBB)