Acute respiratory infections are the leading cause of morbidity in children. They account for 50-60% of children’s first visits to the doctor. Viruses (in more than 90%) and bacteria are the most frequent causative agents; their relative importance varies, depending mainly on the site of infection and child’s age. The commonest bacterial pathogens are beta haemolytic – streptococcus of group A, Streptococcus pneumoniae, Haemophilus influenza, Staphylococcus aureus and Mycoplasma pneumoniae. The principal antibiotics prescribed as drugs of first choice for the treatment of bacterial infections include penicillins, aminopenicillins, macrolide antibiotics and, for severe infection of the lower respiratory tract, epiglotis or bacterial tracheobronchitis, cefuroxime or one of the beta lactamase-resistant antibiotics, alone or in combination that is effective on the most common bacterias. Failure of antibiotic therapy is most often due to improper indication. Early identification of etiologic agent is not always possible. Good knowledge of the clinical picture of acute respiratory infections as well as the available bacteriological tests are crucial for rational use of antibiotics in children.