Objective To describe the effect of evidence-based point-of-care algorithms and rules, based on guideline recommendations, on the overuse of therapies for bronchiolitis.Study design Prepostintervention for infants < 1 year of age admitted with a first-time episode of bronchiolitis.Data collected for guideline-eligible patients discharged between January 15, 2002, and March 27, 2002, were compared with data collected for guideline-eligible patients discharged from the hospital with a diagnosis of bronchiolitis during the same time period in the first 5 years after the original guideline implementation (1997 to 2001).The primary outcome of interest was use of bronchodilator therapy.Secondary outcomes included use of guideline order sets, resource utilization, length of stay, and readmission.Results A total of 256 patients from 2002 were compared with 1272 historic patients.In 2002, the odds of receiving any bronchodilator, more than 1, more than 2, and more than 4 bronchodilators were all significantly less than predicted by the 1997 to 2001 year-to-year trend.The odds of receiving a nasopharyngeal wash for respiratory syncytial virus and a chest radiography (OR=0.680, CL=0.476, 0.973) were also significantly lower than what was predicted from use trends of previous years.Conclusions Evidence-based point-of-care instruments can have a significant effect on unwarranted treatment variation. Objective To describe the effect of evidence-based point-of-care algorithms and rules, based on guideline recommendations, on the overuse of therapies for bronchiolitis .Study design Prepostintervention for infants <1 year of age admitted with a first-time episode of bronchiolitis Data collected for guideline-eligible patients discharged between January 15, 2002, and March 27, 2002, were compared with data collected for guideline-eligible patients discharged from the hospital with a diagnosis of Bronchiolitis during the same time period in the first 5 years after the original guideline implementation (1997 to 2001). The primary outcome of interest was use of bronchodilator therapy. Secondary outcomes included use of guideline order sets, resource utilization, length of stay, and readmission. Results A total of 256 patients from 2002 were compared with 1272 historic patients. In 2002, the odds of receiving any bronchodilator, more than 1, more than 2, and more than 4 bronchodilators were al significantly less than predicted by the 1997 to 2001 year-to-year trend. The odds of receiving a nasopharyngeal wash for respiratory syncytial virus and a chest radiography (OR = 0.680, CL = 0.476, 0.973) were also significantly lower than what was predicted from use trends of previous years. Conclusions Evidence-based point-of-care instruments can have a significant effect on unwarranted treatment variation.