In our hospital, the minimum inhibitory concentration of 100 MRSA isolates in 2003 for teicoplanin is 2 mg/L. Due to its time-dependant bacteriocidal effect, the trough level should exceed 10 mg/L, particularly in the elderly, for MRSA bacteremia. However, it is known that standard dosage of teicoplanin often produces inadequate serum trough levels, and MRSA infections may recurred. Therefore, to evaluate the loading dose required to achieve therapeutic concentration timely, we compare the trough levels between those given standard dose (6 mg/Kg) and those given increasing loading dose (12 mg/Kg). We also monitor the occurrence of adverse drug effects and clinical response.