Objectives. Automated, microprocessor-controlled, closed-loop mechanical ventilation has been used in our Medical Intensive Care Unit (MICU) at the Hadassah Hebrew-University Medical Center for the past 15 years; for 10 years it has been the primary (preferred) ventilator modality.Design and setting. We describe our clinical experience with adaptive support ventilation (ASV) over a 6-year period, during which time ASV-enabled ventilators became more readily available and were used as the primary (preferred) ventilators for all patients admitted to the MICU.Results. During the study period, 1 220 patients were ventilated in the MICU. Most patients (84%) were ventilated with ASV on admission. The median duration of ventilation with ASV was 6 days. The weaning success rate was 81%, and tracheostomy was required in 13%. Sixty-eight patients (6%) with severe hypoxia and high inspiratory pressures were placed on pressure-controlled ventilation, in most cases to satisfy a technical requirement for precise and conservative administration of inhaled nitric oxide. The overall pneumothorax rate was less than 3%, and less than 1% of patients who were ventilated using only ASV developed pneumothorax.Conclusions. ASV is a safe and acceptable mode of ventilation for complicated medical patients, with a lower than usual ventilationcomplication rate.