We compared demographic and clinical characteristics of pneumonia with and without pleural fluid (PF and Pn, respectively) in hospitalized children younger than 5 years in southern Israel, between 2002 and 2011. Overall, 108 PF and 5811 Pn episodes were recorded. Children with PF were older. Prematurity (6.6% vs 14.0%) and asthma (9.9% vs 23.5%) were less common in PF. Mean temperature and saturation were higher in PF while hemoglobin and sodium levels were lower in PF compared with Pn. Nasal washes were obtained in 30.6% and 39.9% of PF and Pn episodes, respectively, with respiratory syncytial virus identified more commonly in Pn (24.2% vs 42.3%). Streptococcus pneumoniae was identified in 5.2% and 0.9% of blood cultures in PF and Pn, respectively. In conclusion, PF differed from Pn in demographic and clinical characteristics, possibly due to differences in etiology. Although both diseases are considered bacterial, a high proportion of viral etiology was found in both, especially in Pn.