There is concern about the increasing tobacco consumption in developing countries, especially in urban communities. Little information is available on the prevalence and determinants of smoking in black townships in South Africa. We therefore conducted a survey of the smoking practices in three such townships in Cape Town, in which 673 higher primary schoolchildren and 1320 adults were interviewed using a WHO questionnaire translated into Xhosa. Results were analysed using a multiple logistic regression model. In higher primary schoolpupils, boys smoked much more than girls [adjusted odds ratio (ORa) = 17.8; 95% confidence interval (CI): 5.2-60.9]; and smoking prevalence increased with age (ORa = 1.6; 95% CI: 1.3-1.9), peer pressure (ORa = 4.4; 95% CI: 1.9-6.9), and poor health knowledge (ORa = 3.1; 95% CI: 1.6-5.8). In adults, smoking prevalence was 53% in men compared to 6% in women. In men, an urban experience of 6 or more years was significantly associated with smoking (ORa = 1.9; 95% CI: 1.2-3.0) after adjustment for age, health knowledge and occupation. No association was found between level of education and smoking prevalence. Men in higher paid occupations smoked more than those in low paid occupations (ORa = 1.7; 95% CI: 1.0-2.8). Unemployment, however, was not associated with smoking prevalence. The findings emphasise the need for primary prevention of smoking in women and boys. Urbanisation and increased earning power appear to boost tobacco consumption in the absence of active anti-smoking efforts.