To investigate the known and new factors associated with uninvestigated dyspepsia (UD), we surveyed 8600 Chinese navy personnel with offshore training shorter than 1 month or longer than 9 months per year. All respondents were required to complete a questionnaire covering demographics, the Chinese version of the Rome III survey, eating habits, life styles, and medical and family history. The response rate was 94.3% (8106/8600) with 4899 respondents qualified for analysis, including 1046 with offshore training and 3853 with onshore training. The prevalence of UD was higher in the offshore group than in the onshore group (12.6% vs. 6.9%, P<0.001), with a general prevalence of 8.1%. The subjects with offshore training were more likely to suffer from UD and postprandial distress syndrome (OR=1.955, 95% CI 1.568-2.439, P<0.001 and OR=1.789, 95% CI 1.403-2.303, P<0.001, respectively). The multivariate logistic regression analysis showed UD was associated with offshore training (OR=1.580, 95% CI 1.179-2.118, P=0.002), family history (OR=1.765, 95% CI 1.186-2.626, P=0.005) and smoking (OR=1.270, 95% CI 1.084-1.488, P=0.003), but not with alcohol drinking. The association between dysentery history and UD was undetermined/borderline (P=0.056-0.069). In conclusion, we identified offshore training as a new factor associated with UD, and also confirmed 2 known associated factors, family history and smoking.