This study describes the impact of undiagnosed and diagnosed asthma on quality of life in schoolchildren aged 7-10 years and their caregivers in a cross-sectional community-based study. Diagnosed asthma was defined as the parents' confirmation of a physician's diagnosis of asthma. Undiagnosed asthma was defined by asthma symptoms combined with airway reversibility or bronchial hyperresponsiveness. Quality of life was evaluated in all children with asthma and a sample of healthy controls by the Pediatric Asthma Quality of Life Questionnaire, and by the Paediatric Asthma Caregiver's Quality of Life Questionnaire. We studied the impact of breathing problems on school absence. Compared with healthy controls, quality of life scores among children and their caregivers were lower if the child had asthma (P < 0.05), with lowest scores in diagnosed asthma (P < 0.05 compared with undiagnosed asthma). Children with asthma reported more school absence (P < 0.05), with highest absence rate in those with diagnosed asthma. In conclusion, both undiagnosed and diagnosed asthma have a significant impact on the quality of life of both children and their caregivers.