Ventilatory techniques are only a part of the weaning process, that also includes medical therapy, physiokinesitherapy, nutrition, psychological support and nursing. Traditional ventilatory techniques used in weaning are: T-piece trials (alternated with assist-control ventilation (ACV)), pressure support ventilation (PSV), intermittent mandatory ventilation (IMV) and continuous positive airway pressure (CPAP) ventilation. None of these techniques has been demonstrated to be better than the others, and the physician must be prepared--to try alternate strategies according to the kind of patient. Noninvasive mechanical ventilation (NIMV) can be successfully used in weaning from invasive mechanical ventilation. Furthermore, NIMV by nasal or facial mask has been successfully used in the treatment of acute respiratory failure (ARF) due to various pathologies. In these cases, the weaning trial has an immediate beginning, since noninvasive ventilation is performed alternatively with spontaneous breathing after the early phase of ARF.