An International Study of Asthma and Allergy in Childhood (ISAAC) revealed a wide range of prevalences of childhood asthma in the world. Lao PDR had no such epidemiological data yet. This study aimed to investigate the epidemiology of asthma, rhinitis, and eczema in children in the country. A cross-sectional study was conducted in Vientiane City, the capital of Lao PDR, in 1997 using the ISAAC questionnaire. From three primary schools and one high school, 395 children, age 6-7 years, and 468 children, age 13-14 years, were chosen. The prevalence of asthma for children aged 13-14 years in Lao PDR was 25.6%, which ranks the highest in international asthma prevalence. The prevalence in allergic-rhinoconjunctivitis of children was 24.4% and atopic eczema was 7.1%. Contrary to generally accepted risk factors, there were no associations revealed between asthma prevalence and smoking of family members (especially mothers), intake of fish/meat, and male gender.