Teicoplanin was evaluated in 25 severe infections caused by Gram-positive bacteria alone [13], in combination [9], alone then in combination [3], in an open study. Of 22 infections that could be evaluated, there were 18 cures and improvements (81.8%), 2 recurrence and 2 failures. Serum concentrations are unpredictable and steady after 5 days i.v. teicoplanin. Trough and peak concentrations are respectively less than 5 mg/l and less than 20 mg/l in 13 infections and higher in 9, unrelated with success or failure. A trough concentration greater than CMI and kind of infection seem deciding. The choice of the antibiotic combined with teicoplanin warrant more data.