Clinical differentiation between infants with „bronchiolitis“ and „acute obstructive bronchitis“ is unclear and confusing. And while some believe that it is only a semantic problem, others believe that from the etiopathogenic point of view they are different entities. We retrospectively analyzed clinical characteristics of infants who were hospitalized and treated at the pediatric clinic of KBC Rijeka under the diagnoses " bronchiolitis " (n = 35, 21 boys (60 %)) and those with the diagnosis of " acute obstructive bronchitis " (n = 43, 32 boys (74 %)) in the period from 2011 to 2014 . At the time of the hospitalization, the average age of infants with bronchiolitis was significantly lower than the average age of infants with acute obstructive bronchitis. Infants with bronchiolitis also had a lower average gestational age, birth weight , oxygen saturation of hemoglobin and a lower average value of CRP in serum. In both groups of infants, inhalational bronchodilator Salbutamol, was eaqually administered. Adrenaline was administered to only one infant with bronhioloitis. Systemic administration of corticosteroids was slightly more frequent in infants with bronchiolitis. Complications in the form of bacterial infections were sporadic in both groups and that was the reason that administratin of beta - lactam antibiotics group was not high .The most used antibiotic was azithomycin, especially with the group of infants with bronchiolitis. Hospitalization of infants with bronchiolitis was significantly longer. None of the infants were mechanically ventilated. Positive anamnestic data of atopy in the infant's family was equally represented in both groups, while infants with acute obstructive bronchitis were more frequently exposed to cigarette smoke