dCommunity-acquired pneumonia (CAP) is an important childhood health problem. Penicillin remains appropriate for treating children with CAP. Clinical data are lacking on disease evolution in children treated with different posologic schemes of aqueous penicillin G. To assess if there were differences in disease evolution between children with CAP treated with 6 or 4 daily doses of aqueous penicillin G, we reviewed the medical charts of hospitalized patients 2 months to 11.5 years of age. Pneumonia was radiologically confirmed based on the detection of pulmonary infiltrate or pleural effusion on the chest radiograph taken on admission and read by a pediatric radiologist blinded to the clinical data. The total daily dose of aqueous penicillin G was 200,000 IU/kg of body weight. Data were recorded on admission, during disease evolution up to the 7th day of treatment, and at the final outcome. The results of hospitalization and the daily frequency of physical signs suggestive of pneumonia were assessed. The subgroups comprised 120 and 144 children who received aqueous penicillin G in 6 or 4 daily doses, respectively. Children >5 years of age were more frequent in the 4-daily-doses subgroup (16.0% versus 4.2%; respectively, P ؍ 0.02). There were no differences between the compared subgroups in terms of final outcomes, lengths of hospitalization, durations of aqueous penicillin G use, frequencies of aqueous penicillin G substitution, or daily frequencies of tachypnea, fever, chest retraction, lower chest recession, nasal flaring, and cyanosis up to the 7th day of treatment. The studied posologic regimens were similarly effective in treating children hospitalized with a radiologically confirmed CAP diagnosis. Aqueous penicillin G (200,000 IU/kg/day) may be given in 4 daily doses to children with CAP. C ommunity-acquired pneumonia (CAP) is an important childhood health problem that accounts for approximately 1.396 million child deaths (1) and 154 million cases (2, 3) annually among children under 5 years old around the world. In clinical practice, it is not routinely possible to identify the etiological agent of the disease (4). Based on a wide range of evidence, Streptococcus pneumoniae is recognized as the most common bacterial agent of CAP (5). This is the rationale behind choosing antibiotics that target this pathogen (4). That is why penicillin and its derivatives remain the appropriate antimicrobial agents to treat children with CAP (6). When hospitalization is required, the first-line drug is intravenous aqueous penicillin G (7).In the 1990s, pneumococcal resistance to penicillin had been widely recognized as a potential problem but the increased dose of penicillin was shown to be effective in overcoming this problem as long as the infection did not affect the central nervous system (8). This finding may be explained by the time-dependent killing characteristic of penicillin (9). That is, the period of time during which the level of penicillin in serum is higher than the MIC is predictive of the therapeutic eff...