Asthma is characterized by variable airflow obstruction and increase in bronchial responsiveness. It has a tendency to destabilize and get worse at night. Recent studies have shown that there are strong indications of increased association between asthma and obstructive sleep apnea syndrome. In a study it is reported that children were five times more likely to have experienced snoring if they reported wheezing in the last 12 months. In a similar research it is reported that the odds ratio of a child with asthma to have habitual snoring was 7,45%. The odds ratio of an adult with asthma to have snoring and/or apneas is 17,9% and 14,3% respectively. Asthma and obstructive sleep apnea syndrome might be linked because of common risk factors and path mechanisms such as airway inflammation, obesity, gastroesophageal reflux and sex-related differences. However, the exact mechanisms are yet unclear. Furthermore it is yet unclear if asthma leads to obstructive sleep apnea syndrome οr vice versa. Pneumon 2006, 19(3):216-222.