Data obtained as part of our routine drug monitoring of teicoplanin therapy (therapeutic drug monitoring, TDM) in adult critically ill patients being treated for suspected or documented Gram-positive multiresistant infections were assessed, retrospectively. Data were available for 202 patients (146 male, 56 female; age 58 +/- 16 years) with a total number of 829 teicoplanin trough plasma levels (C(min)) assessed. The percentage of patients with adequate teicoplanin concentrations (C(min) >/= 10 mg/L) during the treatment period substantially increased from 3.2% on day 2, to 35%, 70%, 90% and approximately 95% on days 4, 7, 11 and 15, respectively. The findings suggest that optimal teicoplanin therapy was achieved only after at least 4, and probably 7, days of therapy in most cases, mainly because of a failure to use an appropriate loading dose. Among the possible causes for the reluctance to use a loading dose, concern over the potential nephrotoxicity of teicoplanin was a major factor. We conclude that loading doses of teicoplanin (6 mg/kg every 12 h for at least three doses) must be considered mandatory in all patients, regardless of their renal function, to enable optimal drug concentrations to be achieved early in the treatment period. Subsequently, TDM is important to ensure that dose regimens are optimized to the individual requirements of the patients.