Antibiotic treatment of community-acquired lower respiratory tract infections in children remains widely empiric since the determination of the causative agent is difficult and rarely done. Antibiotic therapy is not necessary in all cases since viral infections are frequent. Antibiotic choice must take in account the possibility of pneumococcal infections. Pneumococci are not the most frequent causative agent but always provoke severe infections with a risk of death and amoxicillin is the first-line choice, with high doses (100 mg/kg/d) because of the emergence of strains with a reduced sensitivity to penicillin. In younger children, Haemophilus influenzae infections are frequent and clavulanic acid must be associated. When intravenous route is required, 3rd generation cephalosporins are useful. The clinical failure of beta-lactams antibiotics is widely due, after the age of two years, to a Mycoplasma pneumoniae infection and a macrolide is required as second-line choice. Markers specific of viral infection are needed in children to reduce antibiotic prescription.