Blood-gas (pO2, pCO2) and pH-changes of venous (v.jugularis interna) and arterial (A.femoralis) blood samples, furthermore glucose utilization and lactate-, pyruvate-production of brain were investigated during electroconvulsive treatment in relaxation of 45 psychotic patients. The blood-gas values and substrate concentrations were statistically evaluated and represented in a function of the characteristic phases of the postconvulsive EEG-activity. A correlation was found between the glucose metabolism of the brain and the postconvulsive recovery of EEG. The restitution of postconvulsive brain metabolism runs discontinuously in the first 12 minutes of postconvulsive state. In the phase of electric silence and periodic delta-waves the brain metabolism was shifted to anaerobic direction. During the treatment no anoxic anoxia or acidosis takes place during the seizure activity and restitution, the measurable metabolic changes are moderate and supposedly play no important role in the "effect" of treatment.