The long term effects of treatment with xamoterol in 14 patients aged 44-73 with mild to moderate heart failure as a result of ischaemic heart disease are reported. After 18 months' treatment with xamoterol, patients were assessed in a randomised double blind crossover comparison of xamoterol (200 mg twice a day) and placebo, each given for one month. Compared with placebo, xamoterol significantly increased exercise duration and work done on a bicycle ergometer and reduced the maximum exercise heart rate. Assessment of symptoms and activities at 12 months by visual analogue and Likert scales showed a trend towards the relief of symptoms of breathlessness and tiredness and an improvement in activity. There was an improvement in the clinical signs of heart failure and no haemodynamic deterioration over a 12 month period as assessed by ejection fraction. The improvement in exercise tolerance, symptoms, and activities was sustained for 18 months without side effects or development of tolerance.