Background: Cigarette smoking constitutes a major threat to the health and wellbeing of teenagers. While smoking has been on decline in the developed countries, the reverse is the case in developing countries. The aim of this study was to determine the age of initiation, determinants and prevalence of cigarette smoking among teenagers in Mushin Local Government Area of Lagos state, Nigeria. Materials and Methods: This was a descriptive cross-sectional study among 475 teenagers selected by multistage sampling. A pre-tested, structured, interviewer-administered questionnaire was used for data collection. The study was carried out in November, 2014. Results: Response rate was 84.6%. Mean age of the respondents was 16.4±1.65years. Range and mean age of initiation of cigarette smoking were 7 to 17 years and 12.0±3.32 years respectively. Teenagers who were above 15 years (OR:5.13, 95%CI: 0.87-30.26), males (OR:5.19, 95%CI: 1.57-17.18), married (OR:8.41, 95%CI: 1.04-63.35), had ≤primary school education(OR:4.31, 95%CI: 1.07-17.33), influenced by friends(OR:308.84, 95%CI: 84.87-1123.81), and influenced by advertisements (OR:27.83, 95%CI: 3.92-197.64) were more likely to have initiated cigarette smoking. Furthermore, teenagers who were males (OR:12.77, 95%CI: 2.90-56.28), married (OR:19.24, 95%CI: 2.05-180.45), had ≤primary school education(OR:7.85, 95%CI: 2.37-26.01), influenced by friends(OR:28.56, 95%CI: 10.86-75.07), and influenced by advertisements (OR:5.95, 95%CI: 1.72-20.61) were more likely to be current cigarette smokers. In addition, 24.9% had initiated cigarette smoking while 14.7% were current smokers of cigarette. Conclusions: Mean age of initiation of cigarette smoking was 12.0±3.32 years. Determinants of cigarette smoking were age, gender, marital status, educational background, friends and advertisements. Life time prevalence of cigarette smoking was higher than prevalence of current cigarette smokers. Cigarette smoking reduction programs should take these factors into consideration.
