Pneumococci is the number one pathogen causing pneumonia and bacteraemia in children in France. After H. influenzae, it is the second most frequent cause of conjunctivitis and otitis as well as purulent meningitis in 3-month to 3-year-old children (a situation which will undoubtedly be modified by Hib H. influenzae b vaccinations). It also predominates in bronchial superinfections and occult bacteraemia. Penicillin G. has been given for pneumococci infections for years leading the development of resistant strains (20.1% of the strains isolated in France in 1992 were resistant to beta-lactamines. Other resistances include macrolides (44% of the strains), tetracyclins (28%), cotrimoxazol (32%), chloramphenicol (25%) and erythromycin-sulphisoxazol (20%). Thus no other family of oral antibiotics can be successfully substituted for beta-lactamines for routine treatment. Lifestyle and health care organization is a major factor of risk which could explain why the incidence of resistant strains is greater in high density urban populations or in countries were young children are cared for in groups. Therapeutic strategies for easily accessible localizations (septicaemias, pneumonia) can be easily established on the basis of minimal inhibiting concentrations, but for certain sites (otitis, meningitis) more problems are raised. For example, the probability of resistance to penicillin R in acute otitis has been estimated at 75% for children living in the Paris area. We therefore recommend amoxillin (150 to 200 mg/kg/day) or pristinamycin or possibly ceftriaxon (50 mg/kg/day during 3 days). Similar probabilistic strategies are established for purulent meningitis and other childhood pneumococci infections.