The aim of this paper was to study the prevalence of asthma among Saudi schoolchildren aged 7-12 years. A cross-sectional study of 3300 schoolchildren living in three different regions of Saudi Arabia (average 9.32 years, 56% boys and 44% girls) was conducted between January 1986 and January 1990. A self-administered questionnaire was used to collect details of age, sex, area of residence, occupation, education level of parents, asthma, hay fever, cough, wheezing, exposure to pets and animals, parental smoking, and parental history of asthma. The results showed that children with wheezes occur more commonly in Jeddah with 12.6%, Riyadh with 11.9% and Dammam with 6.6%. The frequency of hay fever is significantly more common in each area than wheeze, but once again is most common in Jeddah, with up to 24% of the children complaining of nasal symptoms compared with 17% in Riyadh and 12.1 % in Dammam. A very clear family history of asthma is reported countrywide in that 35.9% of wheezy children have a mother with asthma and 40.7% of these children have fathers with asthma. This contrasts with 8.6% of non-wheezy children with either parent with asthma. A similar pattern is seen with hay fever symptoms with 27.1% of wheezy children having a mother with hay fever symptoms and 22.8% of fathers, compared with 9% of non-wheezy children with either parent with hay fever symptoms.