Smoking continues to be one of the most important health burdens worldwide. Aim: To describe smoking habits and associated risk factors in the population of Santiago, Chile. Material and methods: A cross sectional study of a representative sample of the population, from 16 to 64 years old, residents of Santiago, Chile (total population: 3,237,286). A structured interview that included questions about use of tobacco, the CIS-R interviews, used for common mental disorders, were applied. Results: From the sample of 4,693 households, 3,870 people were interviewed (52.2% women, 47.8% men) and 10% refused. Forty percent of the population currently smoked (52.5% men, 47.8% women). «Being a current smoker» was associated with being younger than 55, male sex, and having a common mental disorder. Discussion: Smoking is highly prevalent in Chile, as compared with developed countries and with some developing countries. Gender differences in use of tobacco have decreased. A higher risk of smoking for people with mental disorders is confirmed (Rev Méd Chile 2003; 131: 873-80)