Objectives(a) To examine the intra-observer reliability of the Malay language versions of two international respiratory questionnaires, i.e. the International Study of Asthma and Allergy in Children (ISAAC) and the American Thoracic Society (ATS) questionnaires, and (b) using the more reliable of these questionnaires, to estimate the prevalence of asthma and allergy related symptoms in an ethnically homogenous inner city community in Kuala Lumpur. Methods:The study was conducted among 7 to 12 year old school children of Malay ethnic origin living in an inner city area of Kuala Lumpur. The sample consisted of 787 children attending the only primary school in the area. The Malay versions of both questionnaires were administered twice, one month apart, and were completed by parents. Agreement between the first and second responses to the same questions were assessed by Cohen’s kappa. Kappa values <0.4 were indicative of poor intra-observer reliability, 0.4 - 0.59 moderate reliability, 0.6 - 0.79 good reliability and >0.79 excellent reliability. Results:77.9% and 36.3% of parents responded to the first and second administrations of the questionnaires respectively. Kappa values of >0.4 were obtained in 15/16 (93.8%) and 17/27 (63.0%) questions of the ISAAC and ATS questionnaires respectively. Excellent kappa values were obtained in 4/16 (25%) questions of the ISAAC questionnaire versus only 1/27 (3.7%) questions of the ATS questionnaire. From the ISAAC questionnaire, all questions on wheeze had good reliability while those on asthma had excellent reliability. Questions on allergic symptoms had poor to moderate reliability. In contrast, from the ATS questionnaire, questions on wheeze had moderate reliability while questions on asthma were excellently reliable. Questions on allergic symptoms had moderate to good reliability while those on cough, phlegm and bronchitis had poor reliability.