Background:  bronchial asthma is a heterogeneous disease characterized by chronic airway inflammation. It is defined by the history of respiratory symptoms such as wheeze, shortness of breath, chest tightness and cough that vary over time and in intensity, together with variable expiratory airflow limitation. This definition was reached by consensus, based on consideration of the characteristics that are typical of asthma and that distinguish it from other respiratory conditions. The causes of poorly controlled asthma may lie in any of four major areas: diagnosis, medications, provoking agents, and presence of co-morbid conditions. Aim of the work: this study aimed to assess causes of improper control of bronchial asthma among patients in Port-Said Chest Hospital. Patients and Methods: this retrospective study was done on 100 uncontrolled asthmatic patients selected from outpatient clinic or inpatient wards in Port-Said Chest Hospital, over a period from January to May 2016. Results: non-compliance and uncontrolled co-morbidities were the most common presented causes of uncontrolled asthma (55% for each), however ttt improper represented 32% of cases. Other less common causes were infection, offending drug, improper diagnosis, wrong technique and resistant asthma.