Background: allergic rhinitis (AR) is considered a worldwide health disease therefore the lack of knowledge would result in poor adherence to management and preventive protocols and increasing the prevalence of AR. Objectives: evaluating the knowledge, attitude and practice(KAP) of Saudi adult subjects toward AR in Kingdom of Saudi Arabia (KSA).  Methods: a cross sectional study conducted on 900 Saudi adult subjects admitted to primary health care centers. The subjects were interviewed and filled up a questionnaire including the respondent's demographics, questions related to knowledge, attitude and practice. Results: most of the respondents aged from31-45 years old, 59.7% were females and 49% were graduated from college.30% of participants had a family history of allergic rhinitis and 34% suffered from allergic rhinitis. Inadequate KAP was found among the participants with higher KAP scores related with higher educational degree. But there were no association between KAP level and gender or age. Conclusion: an inadequate knowledge was found among most of respondents thus resulting in poor attitude and practice pattern. Also, higher educational levels were associated with higher KAP scores.