Patients without spleen or with diminished splenic function are at high risk (10-50 times higher than in normal population) of developing life-threatening infections (OPSI). Mortality from OPSI is estimated at 50 to 80% of cases. More frequent causative agents are encapsulated bacteria: Streptococcus Pneumoniae, Haemophilus influenzae type b and Neisseria Meningitidis. The risk of OPSI can be reduced by immunizing patients against these pathogens and by prescribing antibiotic prophylaxis. Continuous antibiotic prophylactic for 2-5 years after splenectomy (longer periods might expose the patients to the risk of antibiotic resistance) with penicillin or amoxicillin/clavulanate acid is mandatory. Asplenic individuals should take empirical antibiotic therapy - so called "self-treatment" - and immediate medical consultation in presence of febrile illness. All patients and their parents should be carefully educated about the risk of infections in order to obtain a good long-term compliance with these recommendations.