We investigated whether hospital-based specialist asthma nurses improved recognition and self-treatment of asthma episodes by patients followed up after attending accident and emergency departments (A&E) for asthma exacerbations. We carried out a randomized prospective controlled trial of adult asthma self-management, following a hospital outpatient nurse consultation in two outer-London District General Hospitals (secondary care centres). The study included 211 adults, over 18 years old (mean age 40 years) who attended for asthma in two accident and emergency departments over 13 months. One hundred and eight evaluable patients were randomized into the control group who continued with their usual medical treatment and were not offered any intervention during the study period. One hundred and three evaluable patients were randomized into the intervention group. They were offered three 6-weekly outpatient appointments with one of two specialist asthma nurses for a structured asthma consultation, after attendance at the accident and emergency department. Following assessment of their asthma treatment and control, the nurses advised patients, through the use of self-management-plans, how to recognize and manage uncontrolled asthma and when to seek medical assistance. Medication and inhaler device type were altered if necessary The primary outcome was patient reported self-management of asthma exacerbations for 6 months. Secondary outcomes were assessed at baseline, 3 months and 6 months. These included home peak flow and symptom diaries, structured telephone questionnaires and audit of general practitioner records to determine utilization of services (6 months before and after A&E). Data were analysed on an intention to treat basis by multiple and logistic regression. The intervention group increased their use of inhaled topical steroids in 31/61 (51%) vs. 15/70 (21%) attacks in controls (OR 3.91 CI 1.8-8.4, P<0.001) and their use of rescue medication in 54/61 (89%) severe attacks vs. 53/70 (76%) controls (OR 2.88 CI 1.1-7.9, P<0.05). Intervention patients had significantly higher (mean 20.1 l min(-1); CI 0.4-39.7; P<0.05) and less variable PEF and significantly lower and less variable symptom scores 6 months after entry. Thirty-four percent of intervention patients vs. 42% controls had severe attacks (61 and 70 respectively, OR 0.96 CI 0.7-1.4) during the 6 months. Intervention patients had fewer days off work than controls in the first 3 months (NS) but similar days off during the 6-month period. Intervention patients had fewer episodes away from work in the first (0.34 vs. 0.54, P = 0.08) and the second 3 months (0.25 vs. 0.30, NS) than the controls. Over 80% of the patients records were audited by their general practitioners; the active group had less routine consultations with the doctor (P = 0.03) and practice nurse (P = 0.03), less consultations for uncontrolled episodes (P = 0.06) and less hospital visits (NS) than the controls. Hospital-based specialist nurses reduced asthma morbidity by improving patient self-management behaviour in acute attacks leading to reduced symptoms, improved lung function, less time off work and fewer consultations with health professionals.