Electrical and mechanical correlates of crural diaphragm activity during swallow-induced and transient lower esophageal sphincter relaxation were monitored in 12 healthy subjects. Simultaneous esophageal manometric, pH, and crural diaphragm electromyogram recordings were performed for 1 hour in the postprandial period. Swallow-induced lower esophageal sphincter relaxation was associated with minimal inhibition of the crural diaphragm, but transient lower esophageal sphincter relaxation was accompanied by marked inhibition of the crural diaphragm. The degree of lower esophageal sphincter relaxation appeared to correlate with the degree of crural diaphragm inhibition during transient lower esophageal sphincter relaxation. Inhibition of crural diaphragm during transient lower esophageal sphincter relaxation may play an important role in facilitating flow across the gastroesophageal junction.