Although pulmonary rehabilitation results in improvement in multiple outcome areas, relatively few studies in the United States have evaluated its effect on healthcare utilization. This study compared aspects of healthcare utilization during the year before to the year after outpatient pulmonary rehabilitation in patients with chronic obstructive pulmonary disease referred to 11 hospital-based centers in Connecticut and New York. Utilization data from 128 of 132 patients who originally gave informed consent were evaluated; their mean age was 69 years and their forced expiratory volume in 1 second was 44% of predicted. Forty-five percent had 1 or more hospitalizations in the year before beginning pulmonary rehabilitation. In the year after pulmonary rehabilitation, there were 0.25 fewer total hospitalizations (P = .017) and 2.18 fewer hospital days (P = .015) per patient and 271 fewer hospital days for the group. Hospitalizations for respiratory reasons also decreased significantly. Most of the reduction in hospital utilization was due to a decrease in intensive care unit days. The number of physician visits decreased by 2.4 in the year after pulmonary rehabilitation (P < .0001); most of this reduction was due to decreased visits to primary care providers. The estimated costs/charges for the aspects of healthcare utilization that we studied decreased by a mean of 4,694 dollars and a median of 390 dollars (P = .0002). This study suggests that pulmonary rehabilitation leads to a reduction in healthcare utilization.