AbstractThe response to intravenous challenge with pneumococcus was examined in asplenic and sham‐operated adult Sprague‐Dawley rats eighteen weeks following surgery. The LD50 was over 2,000‐fold greater in the sham‐operated animals than in the asplenic animals. These results suggest that the age of an asplenic host, the length of time following splenectomy, and the presence of a normal immune system other than the asplenic state do not in themselves confer i