Objective : To evaluate integrated care for asthma in clinical, social, and economic terms. Design : Pragmatic randomised trial. Setting : Hospital outpatient clinics and general practices throughout the north east of Scotland. Patients : 712 adults attending hospital outpatient clinics with a diagnosis of asthma confirmed by a chest physician and pulmonary function reversibility of at least 20%. Main outcome measures : Use of bronchodilators and inhaled and oral steroids; number of general practice consultations and hospital admissions for asthma; sleep disturbance and other restrictions on normal activity; pyschological aspects of health including perceived asthma control; patient satisfaction; and financial costs. Results : After one year there were no significant overall differences between those patients receiving integrated asthma care and those receiving conventional outpatient care for any clinical or psycho-social outcome. For pulmonary function, forced expiratory volume was 76% of predicted for integrated care patients and 75% for conventional outpatients (95% confidence interval for difference -3.6% to 5.0%). Patients who had experienced integrated care were more likely to select it as their preferred course of future management (75% (251/ 333) v 62% (207/333) (6% to 20%); they saved pounds sterling 39.52 a year. This was largely because patients in conventional outpatient care consulted their general practioner as many times as those in integrated care, who were not also visiting hospital. Conclusion : Integrated care for moderately severe asthma patients is clinically as effective as conventional outpatient care, cost effective, and an attractive management option for patients, general practioners, and hospital consultants.