Bacterial infections in recipients of bone marrow and solid-organ transplants remain a major cause of morbidity and death. The cases of 42 children who had undergone transplantation and developed an infection with Streptococcus pneumoniae were retrospectively reviewed. Thirty-four patients had 1 episode of infection, whereas 7 had 2 episodes and 1 had 3 episodes of infection. Solid-organ recipients were more likely to have recurrent invasive disease (P<.02). A total of 31 (74%) of 42 patients were on immunosuppressive therapy, and 74% had been on antimicrobial therapy within 30 days before diagnosis of S. pneumoniae infection. Only 33% of eligible patients had received a pneumococcal vaccine. Twenty-six percent of isolates recovered were not susceptible to penicillin, and 18% were not susceptible to ceftriaxone. Two patients experienced infection-related deaths; one of these had a penicillin-nonsusceptible isolate. The antimicrobial susceptibilities and outcome of infections with S. pneumoniae in patients who have undergone transplantation are similar to those in the general pediatric population.