We describe three cases of nonconvulsive status epilepticus induced by electroconvulsive therapy (ECT). Nonconvulsive status epilepticus is an important differential diagnosis in patients who develop prolonged confusion after ECT. The present cases exemplify the difficulty in defining the diagnosis on the basis of the clinical manifestations. The application of electroencephalography is recommended in monitoring patients with prolonged confusion following ECT. Concurrent drug therapy and ECT is discussed.