In one embodiment, the dressing has a base which is to be adhered to a patient about a catheter site, an aperture in the base to pull a catheter line through and a cover with a window that is folded over and onto the base in a sealed manner. In another embodiment, the dressing has two covers with windows for folding over separate sections of a base to seal in the components of a catheter assembly with multiple catheters extending from a common housing.