Over 1.2 million migrants from Myanmar are currently residing in Thailand. Little information is known about Myanmar youth risk behaviors. This cross-sectional study aimed to determine the prevalence and the factors associated with cigarette and alcohol use, and physical inactivity, among Myanmar youth working in a harbor town in Samut Sakhon Province, Thailand. One hundred and seventy-seven young workers aged 15-24 years, living in the study area, were interviewed by structured questionnaire. About 21.5% were current smokers, 25.4% were alcohol drinkers, and 36.7% were physically inactive. Univariate analysis indicated one variable was significantly associated with cigarette smoking: education level higher than primary school (OR=2.3, 95% CI 1.02-5.0), Three variables were significantly associated with alcohol drinking: married status (OR=2.2, 95%CI 1.02-4.5); non-seafood-processing workers, i e, street vendors, construction laborers, etc. (OR=3.4, 95% CI 1.7-7.1), and high job stress due to supervisor/boss (OR=2.1 95% CI 1.1-4.2). Two variables were significantly associated with physical inactivity: female youth (OR=3.9 95% CI 2.1-7.5), and education level higher than primary school (OR=0.4, 95% CI 0.2-0.8). The prevalence of smoking, alcohol drinking and physical inactivity among Myanmar migrant youths was quite high. Government and non-government organizations should co-operate to provide interventions to reduce youths' risk behaviors.