FROM ASPLENIA TO SEVERE INFECTION: The most serious consequence of asplenia due to absence of the spleen, its resection or its functional failure is the risk of severe infection. RAPIDLY PROGRESSIVE SEPTICEMIA: It is estimated that the risk of death due to septicemia is 200 times higher in splectomized patients than in patients with a spleen. Death occurs within several days or even hours in most of the patients due to overwhelming post-splenectomy infection (OPSI). The bacteria causing OPSI are predominantly pneumococci (50-80% of identified infections) as well as meningococci, Haemophilus sp, and other capsulated bacteria. IMPORTANCE OF AGE: The risk of infection is even greater if asplenia began early in life, either because of rapidly progressive congenital hemotological disease or splenectomy during infancy or early childhood. According to Holdsworth, infectious morbidity in subjects splenectomized before the age of 16 years is 4.4%, mortality reaches 2.2%. In adults, morbidity is 0.9% and mortality 0.8%. PREVENTION OF RECURRENCE: Furthermore, in an asplenic subject or in a patient with a chronic disease threatening the spleen, the development of infectious episodes is an expression of evolving immunodepression, calling for preventive measures against recurrence. Anti-pneumococcal vaccination and antibiotic prophylaxis using penicillin V considerably reduces the incidence of pneumococcal infection in splenectomized subjects.