A 59-year-old man with the diagnosis of endocarditis of the mitral valve due to Streptococcus mitis was treated with penicillin G, gentamicin, and later with clindamycin as inpatient for 3 weeks. Thereafter outpatient therapy with parenteral teicoplanin 3 x per week was initiated. After 17 days of teicoplanin treatment he developed severe diarrhea, and stool samples were positive for Clostridium di~ficile toxin. In addition to the ongoing parenteral therapy with teicoplanin, oral teicoplanin was administered. On the third day of this regimen the diarrhea and other disabling symptoms subsided, and test results for C. difficile toxin became negative. Oral teicoplanin was continued for 10 days and cleared C. difficiIe effectively after treatment as assessed by consecutive stool cultures (until 60 days thereafter). The parenteral administration of teicoplanin could not prevent the onset of C. difficile associated diarrhea in this patient, who previously had been treated with clindamycin. Thus, the administration of parenteral teicoplanin does not seem to be a treatment option for C. difficile associated diarrhea in patients in which oral therapy is not possible.