Purpose: The presence of pancreatic cyst(s) and the main pancreatic duct dilatation are recognized to be high-risk signs of pancreas cancer. The purpose of this study is to compare ultrasonography and low-dose, non-contrast, enhanced X-ray CT in terms of the detectability of these findings. Subjects and Methods: Subjects were 544 people (346 men and 198 women, age range: 29-88 y.o., mean age: 64.1+10.2 y.o.) who underwent a health checkup during the 21-month period from April 2009 to the end of December 2010. For ultrasonography (US), the fluid-filled stomach method was additionally performed after ordinal abdominal scanning. And for CT, low-dose plain X-ray CT was employed, considering the aim was a health checkup. For 109 people in whom pancreatic cyst (≥5 mm in diameter) and/or pancreatic duct dilatation (≥2.5 mm at the body) were detected with US or CT, magnetic resonance pancreatography or multidetector contrast-enhanced CT was additionally performed within one month to evaluate the findings. Results and Discussion: The sensitivity, specificity, and overall accuracy for the detection of pancreatic cyst were 96%, 94%, and 95%, respectively, with ultrasonography, and 33%, 94%, and 63%, respectively, with CT. The sensitivity was statistically significantly higher (P〈0.0001) with ultrasonography than with low-dose plain CT, and the specificity was same. Regardless of the size or location, the detectability with low-dose plain CT did not exceed that with US. The main pancreatic duct was visualized in all 544 cases with US, but in only four cases (0.7%) with low-dose plain CT. The main pancreatic duct dilatation was confirmed with MRP or contrast-enhanced MDCT in all 67 cases in which it was detected by US. Conclusion: Ultrasonography showed significantly higher accuracy as compared with low-dose plain X-ray CT in the detection of pancreatic cysts and the main pancreatic duct dilatation. For the screening of these high-risk signs of pancreas cancer, the role of ultrasonography is considered to be important.