Previous research has demonstrated differences in pharyngeal size and constriction between normal younger and older adults. The distance between the larynx and the hyoid bone at rest is greater in older persons, as is the anteroposterior width of the pharynx when it is maximally expanded during swallow. In addition, pharyngeal clearing during swallow is reduced with aging. These observations suggest that the aging pharynx undergoes structural changes consistent with atrophy. The purpose of this investigation was to compare pharyngeal wall thickness at rest and when maximally constricted during swallow in younger and older adults. Videofluoroscopic swallow studies were performed on 178 normal adults. Measures of posterior pharyngeal wall thickness were determined at rest and during maximum constriction of the pharynx during a 20-ml bolus swallow. Data were subjected to analysis of variance and Student t test procedures to determine sex and age differences. We found no statistically significant differences between the men and women in either age group, and so we then pooled our data across sex. Mean pharyngeal wall thickness at rest was 0.39 cm (±0.09) in the younger group and 0.30 cm (±0.08) in the older group (p < 0.01). Pharyngeal wall thickness measured at the same point during maximum constriction was 1.08 cm (±0.34) in the younger group and 0.92 cm (±0.36) in the older adults (p < 0.01). Our data suggest that the posterior pharyngeal wall is thinner and does not constrict to the same extent in older subjects compared with younger individuals. These findings contribute to our understanding of differences in pharyngeal strength, swallowing efficiency, and safety associated with aging.