Objective-To measure concentrations of sucrose in the serum of captive dolphins after oral administration of a sucrose solution and determine the suitability of this method for use as a test to detect gastric ulcers. Animals-8 adult captive bottlenose dolphins (Tursiops truncatus). Procedures-Blood samples were collected from the ventral fluke vein of dolphins before and 45 minutes after oral administration of 500 mL of solution containing 25 or 50 g of sucrose; oral administration was achieved by use of gastric intubation. Serum was separated, diluted in a solution of 90% acetonitrile-to-10% water that contained 10 ng of an internal standard (trichlormethiazide)/microliter, mixed, and centrifuged. Supernatant was analyzed by use of liquid chromatography-mass spectrometry-mass spectrometry (LC-MS-MS). Results-Serum sucrose concentrations of dolphins were at or less than the limits of detection before oral administration. Values after administration of sucrose solution varied among dolphins and were higher and more variable after administration of 50 g, compared with concentrations after administration of 25 g. Conclusions and Clinical Relevance-Serum sucrose concentrations in samples collected during routine health evaluations of captive dolphins can be reliably measured by use of LC-MS-MS. Correlating serum sucrose concentrations with endoscopic observations of the gastric mucosa of dolphins will validate this approach for use in screening for the prevalence and severity of gastric ulcers and determining the efficacy of treatment regimens.