Infective endocarditis is an uncommon disease but retains a high mortality. Glycopeptides are used for patients with resistant pathogens, those allergic to penicillins or for those outside the hospital. The once daily administration of teicoplanin and its low toxicity suggest that it would be suitable for use in the long courses required for endocarditis. However, the dosage and combinations to be used require further study. A retrospective review has been made of 104 episodes of endocarditis treated with teicoplanin in 101 patients seen over 7 years. Most patients had been referred to major London hospitals following failure of medical treatment. After three loading doses of 400 mg, teicoplanin was given at a dose of 400 mg/day in combination with other antibiotics such as gentamicin. Follow up was for one year. The most common pathogens were Streptococcus sanguis (15 cases), Staphylococcus aureus (13 cases) and Staphylococcus epidermidis (10 cases). Of 80 patients febrile at the start of treatment with teicoplanin, 63 (79%) lost their fever within a median of 2 days (1-35 days). Cure without surgery was effected in 50 (48%) and 75% of patients survived. Other antibiotics, usually gentamicin or rifampicin, were used in 92 (90%) of patients. Two strains of Streptococcus spp. were said to be resistant but there was no relationship between MIC of teicoplanin and outcome. Pathogens with a high MBC tended to be more likely to resist treatment. Adverse effects resulted in the withdrawal of teicoplanin in 20 cases (19%) but most events were mild and renal deterioration occurred in only five patients. Teicoplanin was effective in the treatment of endocarditis and appeared to be safe given the severity of disease in the patients treated.