Accurate symptom perception on the part of the patient is a critical component of asthma management. Limited data are available about how accurate children and their parents are in evaluating asthma symptoms. This study was designed to determine the symptom perceptual accuracy of families and to identify risk factors associated with inaccurate symptom perception. One hundred children (6-19 years) and their parents evaluated symptoms using subjective (visual analog scales) as well as objective (peak expiratory flow rates) measures of symptom severity. Accuracy was evaluated by comparing the match in zones (based on NHLBI clinical practice guidelines) indicated on the subjective measure with the objective measure. Children and parents were inaccurate about one-third of the time overall. Poor and minority families initially appeared to be less accurate; however, when we adjusted for the child's illness severity, these sociodemographic features were no longer significant risk factors. Children were as accurate as parents. When we evaluated symptom accuracy at "sick times" (when the child's peak flow reading was <80% personal best) accuracy decreased markedly to only about one-third of the episodes being correctly evaluated.