The epidemiology of smoking, factors which motivated students at the University of the Witwatersrand, Johannesburg, to smoke, to continue smoking or to stop smoking, and student awareness of the health hazards of smoking were investigated. Analysis of a random sample comprising 13% of the 12426 full-time undergraduate students at the university revealed that 22% smoked, 17% were ex-smokers and 61% had never smoked. Most of the smokers smoked between 10 and 20 cigarettes a day. The years between the ages of 17 and 19 years appear to be important in determining whether students become regular smokers or stop smoking.