Streptococcus pneumoniae is the leading bacterial cause of paediatric community acquired pneumonia. The life threatening illnesses caused by this organism have been declined significantly after the use of pneumococcal conjugate vaccines. Our herein study was conducted to determine the prevalence of S. pneumoniae isolated from one hundred mechanically ventilated children with severe community-acquired pneumonia in the intensive care unit of Assiut University Paediatric Hospital. Endotracheal aspirates were taken from the cases and were subjected for culture. Discrimination of thirty six S. pneumoniae from closely related Streptococcus species was developed by various phenotypic tests. Our findings strongly recommend the incorporation of vaccine in national immunization schedule which would effectively reduce the incidence of pneumoniae in Egypt.