Background: Asthma is a chronic respiratory disease that is a major health problem in many parts of the world. The aim of the study was to evaluate lifestyle and patient knowledge regarding the severity of bronchial asthma. Subject and method: Research design: A descriptive exploratory design was utilized. Setting: Data were collected from two settings; the outpatient chest clinic at Zagazig University Hospitals and the outpatient clinics of Chest Hospital in Zagazig city. Subject: The study was conducted on one hundred and fifty (150) patients. Tool of data collection: Two tools were used for data collection; Tool (1): was the Patient’s Interviewing Assessment Questionnaire to collect data about patients ‘demographic characteristics and assess the lifestyle and knowledge of studied patients. Tool (2): was Global Initiative for Asthma (GINA) severity scale to determine the severity of asthma. Results of this study showed that the majority (81.3%) of the studied patients had poor life style. About one third (32.0%) of studied patients had satisfactory total knowledge regarding bronchial asthma and 70.0% of studied patients had moderate persistent asthma. Furthermore, relation analysis showed a statistically significant negative correlation between patients’ total knowledge and their disease severity score. Also, both age per year and severity of bronchial asthma were statistically significant positive predictors of the studied patient's lifestyle score. Conclusion: studied patients had an unsatisfactory level of knowledge regarding bronchial asthma and had affected lifestyle recommendations: design and apply training programs to improve patients’ knowledge and lifestyle.