The gold standard for measuring gastric emptying is scintigraphy, either with digestible solids or liquids. Unfortunately, this method is expensive and of limited availability. An alternative could be to use radiopaque markers (ROMs). Our aim was to compare these two tests in healthy volunteers and in patients to see whether emptying of ROMs can substitute for scintigraphic solid emptying. We also intended to see if patients with small intestinal bacterial overgrowth (SIBO) had delayed gastric emptying. Twenty healthy subjects and 21 patients, 11 with SIBO and 10 with insulin-dependent diabetes mellitus (IDDM), were included. A standard meal with a [99mTc]MAA-labeled omelet and 20 ROMs was given. Scintigraphic emptying and ROM emptying were followed simultaneously. Reference values for gastric emptying of ROMs were determined in 50 healthy subjects. The scintigraphic method and the radiologic method correlated significantly in healthy subjects (P < 0.05), and in patients (P < 0.001), when comparing half-emptying time for both methods. Scintigraphic half-emptying time correlated significantly with emptying of ROMs after 6 hr. Six of 11 patients with SIBO (P < 0.02) and 7/10 patients with IDDM (P < 0.02) had delayed scintigraphic emptying of solids using the 95th percentile in the controls as the upper reference value. Gastric emptying of ROMs was, similar to solid scintigraphic gastric emptying, slower in women than in men. In conclusion, scintigraphic emptying of solids and emptying of ROMs are closely correlated. The radiologic method can be used as a simpler and more readily available method. Women have slower gastric emptying of ROMs than men, which necessitates separate reference values. A high proportion of patients with symptomatic IDDM and with SIBO have delayed gastric emptying.