Alcohol is one of the licit psychoactive substances that is commonly used. Alcohol is the third-highest factor for disease burden in the world. In sub-Saharan Africa, the use of alcohol has been reported in relatively high proportions among young people, including adolescents. The present level of alcohol use among adolescent is both a social and public health problem,placing strain on families,schools and health establishments.This has remained a source of worry to parents, schools, society and government because of the attendant negative complications that usually follow. Screening, brief intervention, and referral to treatment (SBIRT) is an evidence-based intervention practice used to identify people who use alcohol and other drugs at risky levels with the goal of reducing and preventing related health consequences, diseases, accidents, and injuries. It is a comprehensive public health approach that provides opportunities for early intervention before more severe consequences occur, it is cost-effective and can be administered to a wide number of people both under clinical and non-clinical settings. AIM The aim of this study is to examine the effect of a brief intervention on alcohol use and associated risks among a sample of senior secondary students in Lagos state, shown to have moderate risk levels of alcohol use. OBJECTIVES The objective of this study is to determine the lifetime and current alcohol use of secondary school students in Lagos state and to determine the effect of a brief intervention on alcohol use and associated risks among the students shown to have and moderate alcohol use risk. METHODS The study was designed to deliver a brief intervention to an obtained sample size of 85 secondary school students with moderate alcohol use. A multi-stage sampling technique was used to select the local government area and the schools within Lagos State, from where the students were selected. At the first stage of sampling; one Local Government Educational Area (LGEA) was selected out of the twenty LGEAs using simple random sampling. In the second stage, two public schools were randomly selected from the chosen LGEA. In the third stage of the sampling processing, the arms of the classes in the school were selected by simple random sampling. In the fourth stage of the multistage sampling, the students to be interviewed were selected by simple random sampling. A total of 367 students from both schools were given a sociodemographic instrument and screened using the Alcohol Smoking and Substance Involvement Screening Test (ASSIST) version 3.0 instrument until the 85 students with moderate alcohol use risk were identified. At baseline, the 85 students (56 males and 29 females) identified as moderate risk alcohol users (scoring between 11 – 26) had an average ASSIST score of 13.80 (SD = 3.221), ranging between 11 – 22. The brief intervention was administered to these 85 students, with each intervention lasting for a minimum of 30 minutes. These same students were reassessed using the ASSIST 3.0 after three months of delivering the intervention. The study data was analyzed with simple percentage analysis, simple arithmetic mean, Chi-square analysis, and paired sample t-test were used as the statistical tools. RESULTS The mean age of the 85 participants was 15.74 years (SD = 1.66). The lifetime and current alcohol use was 48.2% and 42.4% respectively. Religion (χ2 =10.080, p = 0.001) and class of the participants (χ2=10.081, p = 0.001) were significantly associated with lifetime alcohol use. Age (χ2 =7.144, p= 0.028) and religion (χ2 =7.195, p=0.007) were also significantly associated with current alcohol use. A t-value 7.289 (p = 0.000) was obatined from the paired sample t-test, indicating that reduction in ASSIST scores from 13.80 (SD = 3.221) at baseline to 9.12 (SD = 4.516) at month 3 is statistically significant. CONCLUSION The findings of this study further strengthen and support the bulk of the extant literature that screening, brief intervention, and referral to treatment (SBIRT) is effective in significantly reducing alcohol use and related risks among adolescents. This supports the need to incorporate SBIRT as a preventive and early intervention strategy in both clinical and non-clinical settings