Approximately 700 undergraduates studying physiology at community colleges, a liberal arts college, and universities were surveyed to determine the prevalence of four misconceptions about respiratory phenomena. A misconception about the changes in breathing frequency and tidal volume (physiological variables whose changes can be directly sensed) that result in increased minute ventilation was found to be present in this population with comparable prevalence (~60%) to that seen in a previous study (9). Three other misconceptions involving phenomena that cannot be experienced directly and therefore were most likely learned in some educational setting were found to be of varying prevalence. Nearly 90% of the students exhibited a misconception about the relationship between arterial oxygen partial pressure and hemoglobin saturation. Sixty-six percent of the students believed that increasing alveolar oxygen partial pressure leads to a decrease in alveolar carbon dioxide partial pressure. Nearly 33% of the population misunderstood the relationship between metabolism and ventilation. The possible origins of these respiratory misconceptions are discussed and suggestions for how to prevent and/or remediate them are proposed.AM. J. PHYSIOL. 277 (ADV. PHYSIOL. EDUC. 22): S127-S135, 1999.