Bronchial asthma is the most common chronic disease of childhood. Asthma constitutes a serious public health problem all over the world. The optimal asthma control would include minimal chronic symptoms, minimal exacerbations, and no limitation of activities. The aim of the current study was to assess knowledge and practices of mothers of children under five years with bronchial asthma. A descriptive design was used in this study. A convenient sample of 70 mothers was included in the study. The study was carried out in one of the Cairo university pediatric hospitals. The current study revealed that more than one third of children, their age ranged between 4 ¿ 5 years. Three fifth of children had family history of asthma. More than half of children fathers were smokers. There was highly statistically significant difference between urban and rural areas regarding pollution source outside the house. There was highly statistically significant correlation between season of asthma attacks and frequency of attack. The study results concluded that most of mothers had poor knowledge and the majority had poor practices about asthma.