Many pediatricians now recognize the importance of incorporating an assessment of health-related quality of life (HRQL) into their clinical studies. Conventional clinical measures provide valuable information about the status of the affected organ system but they rarely capture the functional impairments (physical, emotional, and social) that are important to the patients in their everyday lives. To obtain a complete picture of a child's health status, both the conventional clinical indices and the child's HRQL have to be measured. Parents do not perceive accurately their children's HRQL, hence it is necessary to obtain the information directly from each child. Children with asthma are distressed by the symptoms (shortness of breath, wheezing, and cough), and they are limited in their day-to-day activities (sports, school, work, and playing with pets). In addition, children are often upset and frightened by asthma attacks, and express anger (younger children) and frustration (older children) because they have asthma. They frequently feel different from their friends and get frustrated that they cannot participate in activities. Disease-specific quality of life questionnaires for children with asthma have been developed. These questionnaires have good measurement properties and validity, and can be used both in clinical trials and in clinical practice to assess the impact of asthma on a child's life. Because one of the aims of treatment is to ensure that the children benefit from treatment, an essential component of clinical assessment of these children should be the evaluation of healthrelated quality of life.