We report on a 35-year-old man who developed pneumococcal meningitis while receiving antiviral therapy with interferon (consensus interferon, CIFN) and ribavirin for chronic hepatitis C. Antibiotic therapy was started four days after the onset of symptoms. Unfortunately, the patient developed a persisting right-sided cochlear hearing impairment. Antiviral therapy led to sustained viral response of hepatitis C. At the age of 14 years he had experienced a hemorrhagic shock after a traffic accident, received multiple blood transfusions and undergone a splenectomy. He had not received vaccination against Streptococcus pneumoniae. This case report reminds us that splenectomized patients without previous pneumococcal vaccination should receive such vaccination before immunomodulatory treatment.