Invasive pneumococcal diseases are the main cause of morbidity and mortality in children. In the Hospital "Prof. Dr. Juan P. Garrahan", between October 1st , 2008 and September 30th, 2011 all invasive pneumococcal diseases with positive blood cultures were retrospectively studied before the implementation of the universal immunization schedule with the 13-valent pneumococcal conjugate vaccine. A total of 124 patients were identified, and their mean age was 48.3 months (range: 1-216). In this population, 58.9% (n: 73) were OVER 2 years old and 89% (n: 65) of them had an underlying disease. The most frequent clinical presentation was pneumonia. The most frequent S. pneumoniae serotypes identified were: 14 (22.5%, n: 25), 6 (14.4%, n: 16), 19 (8.1%, n: 9), 23 (7.2%, n: 8), 1 (6.3%, n: 7), 5 (4.5%, n: 5), and 7 (7.2%, n: 8). Of the S. pneumoniae serotypes in this series, 82.2% is included in the 13-valent pneumococcal conjugate vaccine. Continuous epidemiological surveillance is essential to further identify the epidemiology and study the evolution of invasive pneumococcal disease in Argentina.