Background: The prevalence of asthma has increased considerably in the last few years. This study aimed at assessing the prevalence of asthma and its related risk factors among children in Riyadh, Saudi Arabia. Methods: A cross sectional prospective study was carried out. Pretested well-designed questionnaires were distributed during the period from May to October 2016. Results: Parents of 1700 children out of 4000 have completed the questionnaire with a response rate of 42.5%, 1082 (63.6%) of them were male. Asthma prevalence among girls (14.4%) was higher than boys (12.4%), but this difference was insignificant. Asthma prevalence was significantly higher among Saudi participants (14.4%)compared to non- Saudi (5.9%). Nature of residency, the presence of a plant or presence of pets at home had no significant effect on asthma prevalence. A smoking of family member and a history of asthma in the family had an important association on asthma prevalence rate. The highest prevalence of asthma (29.7%) was among the younger children (<3 years). Symptoms of asthma enhanced during exercise. The positive association between asthma and both cough and breathlessness was noted. Asthma had no effect on schools absenteeism, visiting or admission to hospitals. Body mass index had no effect on the prevalence of asthma. Conclusion: The asthma prevalence rate among children was 13.1%, whereas, smoking and a history of asthma in the family increased this rate. Further studies are recommended to investigate asthma prevalence based on clinical and laboratory diagnosis to explore the link between asthma and obesity.