To investigate the effective usefulness of penicillin prophylaxis in splenectomized patients, we retrospectively focused on a group of sixty-two splenectomized patients affected by thalassemia major. Thirty-six out of 62 has been receiving monthly 1.200.000 Us. of benzathine-penicillin as prophylaxis. The remaining 26 did not receive prophylaxis, but was treated with antibacterial drugs as soon as symptoms of upper respiratory tract infection occurred. During a total period of eleven years of observation we did not observe any pneumococcal sepsis; the incidence of bacterial infections within the two groups is not different. We conclude for the uselessness of penicillin prophylaxis in splenectomized beta-thalassemic patients.