A series of 115 patients was treated with sodium valproate (Epilim) for periods ranging from 6 to 24 months and in dosages ranging from 400 mg to 2400 mg daily. All but six of these patients had intractable epilepsies and had been previously treated unsuccessfully with other anti-epileptic agents. Eighty patients had generalised seizures and 35 had partial seizures which, in 26 cases, were secondarily generalised. Reduction of seizure frequency by over 50 per cent occurred in about 70 per cent of patients with generalised seizures but in only 37 per cent of those with partial seizures. A number of patients reported increased alertness, improvement of mood, increased appetite and improved performance at school. the adverse effects encountered were gastro-intestinal symptoms, weight gain and hair loss.