The antibody response following anti-pneumococcal immunization with a 14-valent vaccine was studied in 54 children, aged 2 to 18 years after splenectomy. Splenectomy had been performed for traumatic, hematologic or immunologic reasons. Antibody titration with respect to 12 serotypes was performed by radioimmunoassay immediately before and one month after immunization. Changes in responses were studied according to the indication for splenectomy and to the vaccine serotype. The main conclusions of this study are the excellent tolerance of immunization, the lack of significant difference between the average responses according to the indications for splenectomy, the obtainment of a titer probably protective for 80% of the patient studied and the confirmation of the low immunogenic character of serotype 6A. These results suggest that anti-pneumococcal prophylaxis by immunization can be highly recommended before splenectomy but it can also be performed after surgery.