The aim of this work was to study smoking habits, alcohol and drug use and living standards in a random sample of 1000 dwellings and 4700 people of Santiago through periodic surveys during 1993 and 1994. Forty nine percent of dwellings had at least one inhabitant that was a daily smoker and 73% had at least one occasional smoker. Thirty seven percent of subjects older than 15 years were smokers (40% of men and 35% of women), 27% were presumably addicted to tobacco and 16% former smokers. Alcohol abuse had a prevalence of 2.3%. The highest prevalence of smoking was noticed in low socioeconomical strata. Smoking was not related to educational level or emotional disturbances. Frequency of alcohol abuse or marihuana use was 8.8 times higher in former smokers and 25 times higher in actual smokers, compared to people that never smoked. Comparing these results with previous population surveys, the prevalence of smoking increased in the period 1971-1986 from 47 to 51% in men and from 26 to 43% in women. On the other hand, during the period 1986-1994 the prevalence decreased from 51 to 40% in men and from 43 to 35% in women.