A prospective controlled study of the safety of various catheter dressing protocols was carried out in 168 patients receiving parenteral nutrition via an infraclavicular central venous catheter. Four protocols were compared: 36 patients received gauze dressings changed three times per week; 31 received OpSite dressings changed every 7th day (OpS-7), 32 received Opsite changed every 10th day (OpS-10), and 69 received OpSite changed twice weekly (OpS-ICU). Mean duration of parenteral nutrition was approximately 2 weeks and all groups were well matched except that OpS-ICU patients suffered more frequently from an acute illness. Catheter-related sepsis was identified by clinical signs of systemic sepsis, positive peripheral venous blood and catheter-tip cultures and/or defervescence of fever after catheter removal. Catheter-related sepsis rates were low in all groups: 1/36 for Gauze, 0/31 for OpS-7,1/32 OpS-10, and 2/69 for OpS-ICU. Septicemia attributable to causes apart from catheter sepsis occurred in two, two, three, and four patients, respectively. Bacterial colonization of skin beneath OpSite was no more common in the OpS-10 than in the other groups. Signs of inflammation at catheter insertion sites were common in all groups but did not relate closely to skin colonization. OpSite can be safely applied to central venous catheters inserted under strict aseptic conditions, even in patients with open septic drainage. Dressings can be left in place for 7 days with a margin of safety lasting to 10 days, thus saving on cost of materials and nursing time.