Study design: Retrospective review of patient medical records comparing the outcomes of two groups of individuals with high-level (C3-4) tetraplegia ± those with high-volume and those with low-volume mechanical ventilation. Objectives: To determine if higher volume mechanical ventilation contributes to faster weaning from the ventilator with fewer complications in individuals with ventilator dependent high-level tetraplegia. Setting: A Model Spinal Injury Center, located in Colorado, USA, which treats patients referred from throughout the Rocky Mountain region as well as other states. Methods: The medical records of 42 individuals with ventilator dependent C3-4 tetraplegia, admitted consecutively to the Rocky Mountain Regional Spinal Injury System between 1983 and 1993, were reviewed. All had required full-time mechanical ventilation upon admission, but had successfully weaned by discharge. They were divided into two groups that di ered with respect to the ventilator tidal volumes used during their treatment and weaning: a large volume group (420 mls/kg of body weight) and a smaller volume group (520 mls/kg of body weight). Results: Though the two groups were equivalent in neurological level and completeness, muscular function, initial spontaneous vital capacity, the weaning method used (T-piece), and ®nal spontaneous vital capacity, those in the large tidal volume group successfully weaned an average of 21 days faster than the lower tidal volume group (37.6 days vs 58.7 days, P=0.02). They also had signi®cantly less atelectasis (P=0.01) than the lower tidal volume group. Conclusion: This research suggests that the use of higher ventilator tidal volumes may speed up the weaning process and lessen respiratory complications. Because of the potential for this to decrease the length and cost of the rehabilitation programs for persons with high-level tetraplegia, further large-scale research is needed to verify these single-center ®ndings.