The anti-convulsive action of dipropyl acetic acid (Convulex) was tested in 21 patients with grandmal seizures (GM) and/or temporal lobe attacks (TL), or with Jacksonian epilepsy. Patients were chosen according to a negative selection system. Results showed that in GM and TL seizures, Convulex constitutes an important addition to the battery of anticonvulsives available today. Action was more potent in GM than in TL attacks. Toxic effects are slight. Treatment had to be discontinued in two patients -- once because of cerebellar symptoms and once because of crowded incidence of seizures. In two cases the patients gained weight. Occasional gastrointestinal complaints disappeared when antacids were administered. No changes were observed with reference to blood count, or to hepatic or renal function. Fatigue set in only when treatment was combined with barbiturates and disappeared again when pre-medication was reduced. Five patients showed an improved state of mind (activation and better communication with others); this psychological action may be considered an additional advantage. Since the action of barbiturates and hydantoins is potentiated by Convulex, pre-medication may be reduced --provided Convulex therapy alone does not seem adequate. Hence, trial treatment with Convulex may also be recommended in those patients who are successfully controlled with barbiturates and hydantoins,but whose daily work schedule is impaired due to fatigue.