This study examined the impact that implementation of guidelines for the management of peripheral intravascular devices had on nurses’ knowledge and practice as well as patient outcome. A pre- and posttest nonequivalent experimental study was conducted in a Hong Kong tertiary care teaching hospital. The results showed that the percentage of correct answers for all questions was significantly higher at the posttest. The overall results also showed significant practice improvement in terms of the flushing agent used, documentation, and site dressing. There also was a decrease in the incidence of extravasation and phlebitis. It was concluded that evidence-based practice is important for improving patient outcomes. Compliance with the guidelines served as an important measure for the prevention of intravascular device-related complications.