Seventy-one patients <5 years of age who were hospitalized with invasive pneumococcal disease were studied in the period between August 2008 and December 2009. The purpose was to determine the proportion of episodes that were coinfected with respiratory virus. Viral coinfection was common (44/71; 62%), with rhinovirus and influenza virus being the most frequently detected. Highly invasive serotypes (1, 5, 7F, 14, 19A) were found in 31 of 71 patients, of whom 15 had viral coinfection (15/31; 48%). Viral detection occurred significantly more often in those episodes caused by nonhighly invasive serotypes (29/40; 72%), suggesting that a viral synergism could help those serotypes to make invasiveness more likely.