Resistance of seizures to anti-epileptic therapy may be due to patient error, or to physician diagnostic and/or treatment error, rather than being truly intractable epilepsy. Increased drug dosage, irrespective of blood levels, a change of drug, or the addition of a second drug, are variously indicated in truly resistant cases. The use of more than two drugs is better avoided, and in some cases reduction of treatment may improve seizure control while lessening side-effects. Repeated assessment of patients with refractory epilepsy is important, as causative or provocative factors may remain latent for long periods. Surgical therapy probably should be used more often and earlier than it now is for epilepsies that are medically intractable.