The discordance between the objective and subjective symptoms of asthma has major effects on proper medication and management. In 2 studies the influence of respiratory sounds in the process of symptom perception underlying breathlessness was investigated in children aged 7-17 years. In Experiment 1, asthmatic wheezing sounds were recorded in 16 children during histamine-induced airway obstruction. Breathlessness correlated significantly with rank order of amount of wheezing, but not with lung function. In Experiment 2, after standardized physical exercise, 45 asthmatic and 45 nonasthmatic children were randomly assigned to (a) false feedback of wheezing, (b) quiet respiratory sounds, or (c) no sound. Asthmatic children reported significantly more breathlessness in the 1st versus the 3rd condition. In conclusion, many asthmatic children were easily influenced by wheezing in their estimation of asthma severity, reflected in breathlessness.