Eighty-three episodes of Gram-positive infection in 82 patients were treated with teicoplanin in an open study. Infectious episodes included endocarditis (6 cases), bacteraemia (7), osteomyelitis (8), pseudomembranous colitis (13), cellulitis (11), urinary tract infection (5), pneumonia (1), wound and post-surgical infections (9) and erysipelas (23). Four patients affected by an overwhelming Gram-positive infection as well as eight cases of Gram-positive-Gram-negative mixed infections received teicoplanin in combination with other antibiotics. The average duration of treatment was 16 days (range 5-70). In pseudomembranous colitis teicoplanin was given by mouth for ten days. Staphylococcus aureus (11 methicillin-sensitive and 13 methicillin-resistant strains) and Clostridium difficile (13 isolates) were the most frequent pathogens. Overall 89% (74/83) of the infections were cured, 3.6% (3/83) improved and 3.6% (3/83) failed. Relapse and superinfection were observed in 2.4% (2/83) and 1.2% (1/83) episodes respectively. All pseudomembranous colitis cases were clinically cured and C. difficile was eradicated in all but one patient. The MIC range, MIC50 and MIC90 (mg/l) of teicoplanin for C. difficile were less than 0.125-0.250, less than 0.125 and 0.250 respectively. Pharmacokinetic studies in patients given a single iv daily maintenance dose of 400 mg showed that the steady-state trough teicoplanin concentrations in serum were reached on day 8. Assays of skin-subcutaneous tissue biopsies showed that teicoplanin penetrated well into these structures. Side effects were observed in six of the 82 treated patients (7.3%) and teicoplanin had to be discontinued in four cases. The results of the study show that teicoplanin is a safe and useful new agent for the treatment of infections caused by Gram-positive organisms, including methicillin-resistant staphylococci and C. difficile.