Exercise-induced bronchospasm limits physical activity in most asthmatic children. Twelve children with stable chronic asthma were enrolled in a physical conditioning program to improve ventilation mechanics and to promote physical activity. The program consisted of eight weekly sessions of one-and-a-half hours each, followed by three months of weekly swimming lessons. The activities were preceded by a warm-up period and interspersed with rest. Premedication with an aerosol bronchodilator or sodium cromoglycate was allowed before training. Cardiorespiratory status was studied before and after the program. The program was well received by the children with no bronchospasm. Five showed improvement in lung volumes and/or flow rates. Bronchial liability remained the same. The basal heart rate slowed in four children. No significant arrhythmia was detected. With continued practice, cardiorespiratory function might improve further. The program should be incorporated as part of the overall management of bronchial asthma.