Weaning a patient from the respirator should be started as early as possible. The right time when to stope artificial ventilation is determined by certain criteria. Pathological processes which might interfere with the weaning process should be corrected beforehand. Incipient septicaemia, peritonitis, circulatory instability and a marked postoperative or posttraumatic rise in intracranial pressure are extrapulmonary contraindications for weaning. Apart from conventional weaning, continuous positive airway pressure ventilation and intermittent mandatory ventilation are discussed.