Objective: To determine the prevalence of excessive alcohol intake (EAI) and cigarette smoking (CS) in schoolchildren of Brazzaville. Methods: This cross sectional survey included a representative population of schoolchildren in Brazzaville (603 schoolchildren divided 325 girls and 278 boys). Results: The prevalence of EAI was 9% (n = 54). The mean age of EAI children was 16.2 ± 1.3 years (range: 13 -18 years) vs 11.4 ± 3.4 years (range: 5 -18 years) for no EAI children (p < 0.001). In logistic regression, the independents determinants of EAI were: age, alcoholism in parent, orphans, siblings, low social level. The receiving operative curve (ROC) of age and EAI shown a sensitivity of 74.1% and specificity of 85.1% for 15.5 years: area under curve (AUC) = 0.891 (95% IC: 0.86 -0.92; p < 0.001). The prevalence of CS was 2.5% (n = 15). The mean age of smokers children was 15.9 ± 1.5 years (range: 13 -18 years) vs 11.7 ± 3.6 years (range: 5 -18 years) for no smokers children (p < 0.01). In logistic regression, the independents determinants of CS were: siblings, migration, orphans, male sex. The ROC of age and cigarette smoking shown a sensitivity of 73.3% and specificity of 73.6% (AUC: 0.839; 95% IC: 0.77 -0.90; p = 0.035) for 14.5 years. Conclusion: Low social level, siblings, addictions in parents were correlate addictions in schoolchildren. It is necessary to prevent the acute and futures complications of this addiction in our children.