Three long-stay, hospitalised schizophrenics who had failed to respond adequately to conventional drug therapy were treated with gamma-linolenic acid and linoleic acid in the form of evening primrose oil. They became substantially worse and electroencephalographic features of temporal lobe epilepsy became apparent. In all three the clinical state dramatically improved when carbamazepine, the conventional therapy for temporal lobe epilepsy was introduced. It can be extremely difficult to distinguish on clinical grounds between schizophrenia and temporal lobe epilepsy, and electroencephalographic studies do not always reveal an abnormality in the temporal lobe syndrome, unless additional procedure such as sphenoidal electroencephalography is undertaken. A trial of therapy with gamma-linolenic acid may prove of considerable value in distinguishing between these two states, so allowing specific therapy to be introduced.