The findings of concurrent esophageal videofluoroscopy and manometry in 15 patients with major disturbances of esophageal motor function were evaluated and the data were analyzed from a fluid mechanical perspective. Each of 153 fluoroscopic barium swallow sequences was analyzed on a swallow-by-swallow basis. Two distinct pressure domains were identified: intrabolus pressure and pressure within a bolus-free contracting esophageal segment. Analyses in terms of these pressure domains showed specific and consistent correlations between the radiographic and manometric findings. Radiography was insensitive to contractions occurring in esophageal segments devoid of bolus fluid, whereas manometry was insensitive to contractions that did not occlude the lumen. It is concluded that using fluid mechanical principles of bolus transport allows meaningful comparison of esophageal motility as recorded by radiography and intraluminal manometry. However, the inherent limitations in the range of physical phenomena recorded by each modality make these techniques complementary for evaluating esophageal motor function.