Four dressing regimens for peripheral venous catheters were studied in a prospective randomized clinical trial with 2088 Teflon catheters: (1) sterile gauze, replaced every other day, and three dressings left on for the lifetime of the catheter; (2) gauze; (3) a transparent polyurethane dressing; and (4) an iodophor-transparent dressing. The four dressings provided comparable coverage, except moisture accumulated more frequently under the transparent dressings 26% to 28% vs 20% to 21% Cutaneous colonization under the dressing was low level and comparable with all four dressings (range, 100.58 to 100.70 colony-forming units). The rate of local catheter-related infection ≥15 colony-forming units) was also low and did not differ significantly (range, 4.6% to 5.9%); no catheter caused bacteremia. Stepwise logistic multivariate analysis showed cutaneous colonization of the insertion site (relative risk [RR] of infection, 3.86), contamination of the catheter hub (RR, 3.78), moisture under the dressing (RR, 2.48), and prolonged catheterization (RR, 1.75) to be significant risk factors for catheter-related infection. These data indicate that it is not cost-effective to redress peripheral venous catheters at periodic intervals; for most patients, either sterile gauze or a transparent dressing can be used and left on until the catheter is removed.