Blood flow in the left gastric artery was measured with an electromagnetic flowmeter in nine conscious beagle dogs. In the fasting state gastric motility and secretion exhibited periodical changes with an average cycle interval of 115.4 +/- 9.7 min. During a quiescent period, when gastric motility and secretion were minimal, the mean blood flow was stable at 33.9 +/- 3.8 ml/min. During the contracting phase each peristaltic contraction was coupled with a rapid fall and rise in blood flow (from 10.5 +/- 1.9 ml/min below to 21.2 +/- 3.8 ml/min above the precontraction levels) in 20-30 s. In addition there was a sustained elevation in blood flow (58.6 +/- 6.4 ml/min at the peak) lasting for 29.1 +/- 2.8 min. The onset of sustained blood flow elevation was preceded by that of motility in 63% of the cycles. In 23% of the cycles blood flow started to rise before the contracting phase began. Pepsin peaks coincided with blood flow peaks in two dogs and preceded the latter in the others. Feeding abolished periodic increases in motility and blood flow. It is concluded that left gastric arterial blood flow is not steady but exhibits dynamic changes in phase with periodic motor and secretory activities of the stomach in fasting conscious dogs.