Background:-Currently dental caries, one of the most common important global oral health problems affecting a large segment of worlds' population. It is the destruction of dental hard a cellular tissue by acidic by-products from the bacterial fermentation of dietary carbohydrates, especially sucrose Objective: To assess the prevalence of dental caries and associated factors of among the military persons in Assosa military camps, Western Ethiopia. Methods: An institution based cross sectional study was conducted from July 15/ 2018 to August15 2018. a total of 423military persons were selected using a simple random sampling method. Data were collected using a structured and interviewer administered questionnaire. Dental examination was carried out for all selected study subjects by trained dental professionals or dental therapists using world health organization (WHO) dental caries diagnosis guideline. first data were collected, entered in to computer using EPI data version3.1 then, the data were exported to the SPSS version 23 for further cleaning and analysis. Various summary statistics were computed to describe the study variables and presented using frequency tables. Bivariate and multivariable logistic regression analysis was carried out to identify factors associated with the dental caries. Variables having a p-value of less than 0.2 in the bivariate analysis were entered to the multivariable logistic regression analysis to control the confounding effects during the analysis. The association between variables was described using the odds ratio at 95% CI and p-value <0.05 Result: A total of 423 study participants were included in the study with 100 % response rate. Majority of the participants (89.4%) were males. The mean (SD) age of the respondents was 28+(1.6) (rage 18—52),(26.5%) were cigarettes smokers. More than half (61%) study participant were alcohol drinkers. The prevalence of dental caries among the military persons was found to be 59.1 %( CI: 53.9%--63.9%). The mean DMFT was 1.66.Person who used fluoridated tooth paste had less caries than those who used none fluoridated tooth paste. Cigarette smokers (AOR=1.64 95%CL: 1.01-2.67), had information about dental caries (AOR=1.94 95%CL: 1.27---2.97) frequency of brushing (AOR= 0.45, 95%CL: 0.24-0.81) were statistically significant factors of dental caries in study area. Conclusion and recommendation: Based on this study, nearly two third of the participants have developed dental caries. Similarly, large number of military persons had risk personal behaviors that could expose them develop dental caries. Cigarette smoking, heard about dental caries, and frequency of brushing habit were positively associated factors to the dental caries in the study area Therefore, regular awareness creation on health impact of behaviors/life /lifestyles using different strategies such as health education, conference, peer education, availing information sources needs to be implemented.