The wire introducer method is a satisfactory technique for management of central venous catheters if bacteriologic monitoring of the removed catheter is used to determine whether the introduced catheter should be allowed to remain. The data indicate that when central venous catheters become infected, they do so through the whole length of the catheter, from subcutaneous tunnel to intravascular tip. An intravenous catheter which produces negative cultures can be safely changed by the introducer method aseptically. An infected catheter must be removed as soon as the diagnosis is apparent, since the replacement catheter will be seeded by the colonized tract. Blood specimens drawn through central venous lines do not reflect the status of the line itself but rather the presence or absence of systemic bacteremia.