Recently, high-concentration barium sulfate has been developed and is used in many medical facilities. This study compared radiation dose using high-concentration and moderate-concentration barium sulfate. The dose was evaluated with an experimental method using a gastric phantom and with a clinical examination. In the former, the dose and X-ray tube load were measured on the phantom with two concentrations of barium sulfate. In the latter, the fluoroscopic dose-area product (DAP), the radiographic DAP and their sum, the total DAP, were investigated in 150 subjects (112 males, 38 females) treated with both concentrations of barium sulfate. The effective dose was calculated by the software of PCXMC in every case. The results of the experimental evaluation indicated that the effective dose and X-ray tube load were greater with high-concentration barium sulfate than with moderate-concentration barium sulfate (p < 0.05). The results of the clinical evaluation indicated that the fluoroscopic DAP was greater with moderate-concentration barium sulfate than with high-concentration barium sulfate (p < 0.05), but the radiographic DAP was quite the reverse, so the total DAP and effective dose were almost same with both concentrations of barium sulfate. We conclude that high-concentration barium sulfate does not increase radiation dose in mass screening for gastric cancer.