OBJECTIVE To assess the prevalence and risk factors of childhood asthma and allergies in Hong Kong and compare with that in Singapore and Great Britain. METHODS Parents of 3618 randomly selected 6- to 7-year-old children responded to a questionnaire prepared by the International Study of Asthma and Allergies in Childhood (ISAAC) together with supplementary questions on risk factors. RESULTS The 12-month prevalences of wheezing, rhinitis symptoms and itchy rash were 9.2%, 35.1% and 4.2%, respectively. Wheezing in the past year was significantly associated with rhinitis symptoms in the past year, itchy rash in the past year, rhinitis interfering with daily activities moderately or severely, kept awake by itchy rash in the past year, parental wheezing (one or both parents), frequent upper respiratory tract infections (URTI), born in Hong Kong and male sex. For girls, the prevalence of wheezing in the past year was lowest when they were born in July/August and highest when born in January/February. CONCLUSIONS The prevalence of allergic disorders in Hong Kong was comparable to that in Singapore and Great Britain. Several potential risk factors such as parental wheezing, frequent URTI, born in Hong Kong, male sex and month of birth in girls were identified.