The purpose of this study was to provide information to improve the management of childhood asthma in Canada. The Student Lung Health Survey (SLHS) was conducted as a stratified and multi-staged cluster survey across Canada in 1996. It included a total of 136 public, private and separate schools in nine health units. The target study population was schoolchildren aged 5 to 19 years. Among all 5-19 years old students, the prevalence of asthma was 13.0%, with the prevalence for males being higher than for females, the adjusted Odds Ratio (OR) was 1.17, (95% CI 1.14-1.19) for males, in comparison with females. The prevalence in the 15-19 age group was higher than that in the 5-9 and 10-14 age group in females, but it was higher in the 5-9 and 10-14 age group than in the 15-19 age group in males. The mean delay from the onset of symptoms to time of first diagnosis was 1, 0.4 and 0.3 years for the 1-4, 5-9 and 10-14 age group respectively. However, there was no delay in the 15-19 group. The prevalence of asthma in Prince Edward Island (17.9%), Halifax (17.1%), and Kingston (16.1%) was higher than that in Saskatoon (10.0%). Sherbrooke (9.7%) and Kelowna (11.9%). The proportion of asthma for students who smoked more than 11 cigarettes per day (OR = 1.41), were exposed to passive smoke in home (OR = 7.29), in car (OR = 4.71), and in school (OR = 4.24) or had a family income less than CAN$40,000 (OR = 1.19), was significantly higher than groups without those factors. Risk factors and socio-economic status such as living conditions and environment, pets or plants in the home, parental education levels also affected the morbidity of asthma. The results of the SLHS study demonstrated the serious burden of childhood asthma, and asthma triggers, living and environmental conditions and lifestyle influence the prevalence and the effects of childhood asthma diagnosis, treatment, and education in Canada. Asthma is still a serious chronic condition for students and it influences their academic performance and their quality of life. The diagnostic methods and the practice guidelines for asthma control are useful for preventing and controlling asthma. These findings provide indications of interventions are being used for the control of asthma in Canada.