Asthma is a complex disorder characterized by paroxysmal airways constriction, an increased responsiveness of the airways to inhaled allergens and inflammatory cells infiltrate. Bronchiolitis in infancy is viewed as a risk factor for childhood asthma, a syndrome characterized by wheezing respiratory distress and the pathologic findings of peribronchial cell infiltration and release of inflammatory mediators. Chemokines are central regulatory molecules in inflammatory, immune, and infectious processes of the lung. To assess the role of MIP-1alpha in bronchial asthma and acute bronchiolitis 30 children (15 diagnosed as bronchial asthma and 15 as acute bronchiolitis) were enrolled in this study. The results of our study showed that levels of plasma MIP-1alpha were significantly higher in bronchial asthma and acute bronchiolitis cases, and there was a positive correlation between plasma MIP-1 alpha level and the severity of the disease suggesting that MIP-1alpha has a pivotal role in mediating the pathogenesis of respiratory tract inflammation in bronchial asthma and acute bronchiolitis. So, it may help to identify novel therapeutic options directed at immunomodulation of bronchial asthma and acute bronchiolitis.