The validity of videofluoroscopic swallowing assessments rests on the understanding that thin, nectar-, honey-, and spoon-thick radiopaque liquids resemble nonopaque liquids, both in their consistency and in the variations in swallowing that they elicit. Tongue movements during sequential swallows of opaque and nonopaque liquids were studied in 8 healthy participants in 2 age groups (less than 30 years, greater than 50 years) using electromagnetic midsagittal articulography. Differences included smaller sip size, longer oropharyngeal transit times, and greater variability in tongue movement patterns with opaque liquids compared to nonopaque liquids, but effect sizes for these differences were small. Transit times were significantly longer for older participants than younger participants. We recommend matching radiopaque bolus size in videofluoroscopy to the patient's habitually preferred sip mass for comparator nonopaque liquids.