Delineated methodologic issues in the study of symptom perception in childhood asthma. A review of past and recent psychophysiological and clinical studies of both adults and children presents the methodologic and analytic approaches that have been applied to quantify perceptual accuracy. Peak expiratory flow rate, forced expiratory volume in the first second, and force expiratory flow can serve as objective measures of asthma. A visual analog scale, a numerical guess, and a categorical description as subjective measures all have clear strengths and weaknesses. Correlational analysis of subjective-objective data, arithmetic differences between subjective guess and objective value, and an error grid categorization can each be applied to calculate an accuracy index on an individual subject. Illustrative examples reveal that the same data lead to different indices depending on the method chosen. Empirical research is needed to standardize various methodologic approaches. Given the increasing prevalence, severity, and morbidity of pediatric asthma, the study of symptom perception may be a critical component in our understanding of asthma management, and will likely lead to useful clinical interventions.