A cross-sectional study was conducted to explore factors associated with alcohol consumption among upper secondary school students in Nakhon Ratchasima Province. A multistage sampling technique was used for selecting 850 students from 6 schools and subjects were classified into 2 groups according to hazardous alcohol drinking (yes = 107, no = 743) by the Alcohol Use Disorders Identification Test (AUDIT). Data were collected by questionnaire from August to September 2005. Descriptive statistics, the chi-square test and multiple logistic regression were used to analyze data. The results showed the percent of hazardous drinking was 12.59. Most of the students were ≤ 16 years old (51.41%) and in the science program (52.68%). Univariate analysis revealed the socio-demographic factors of gender, grade point average (GPA), monthly expenditure, age, and educational level were significantly associated with alcohol drinking (p<0.05). Sibling and peer alcohol intake were associated with hazardous alcohol consumption (p<0.05). Multivariate analysis, after adjusting for age, educational level and gender, revealed only 3 factors associated with male alcohol consumption: peer usual alcohol intake (OR = 23.46, 95% CI = 7.29-75.43) and peer occasional alcohol intake (OR = 5.57, 95% CI = 2.02-15.31), GPA > 3.0 (OR = 0.29, 95% CI = 0.11-0.73). Only 2 factors were associated with female alcohol drinking: peer usual alcohol intake (OR = 63.41, 95 % CI = 9.24-435.31) and peer occasional alcohol intake (OR = 7.94, 95 % CI = 1.89-33.43). As a result, peer groups and close friends should be considered carefully when attempting to reduce the risk of alcohol consumption.