In clinical and experimental settings, the (13)C breath test is performed to measure gastric emptying and has advantages of noninvasiveness and repeatability. We intended to apply the (13)C breath test method to mice with an easy-to-handle solid test meal that is more physiological than liquid meals. Male ddY mice were trained to eat (13)C-acetate-containing pellets as the solid test meal. Thirty minutes after administration of metoclopramide (0.3-3 mg/kg, p.o.) or atropine sulfate (0.3-3 mg/kg, i.p.), mice received the test meal and were placed in chambers. The (13)CO(2) levels in the expired air were measured and the maximum concentration (C(max); per thousand) and the time to reach the maximum concentration (T(max); min) were determined. Metoclopramide significantly and dose-dependently increased C(max) and decreased T(max). On the other hand, atropine sulfate significantly and dose-dependently decreased C(max) and increased T(max). The (13)C-acetate breath test using a solid test meal is sensitive enough to detect both enhanced and delayed gastric emptying of the reference drugs.