AIM: This study aimed at evaluating the outcome of implemented evidence-based clinical guidelines by means of surveying the frequency of thrombophlebitis, nurses' care, handling and documentation of peripheral intravenous cannulae. BACKGROUND: Peripheral intravenous cannulae are frequently used for vascular access and, thereby, the patients will be exposed to local and systemic infectious complications. Evidence-based knowledge of how to prevent these complications and how to care for patients with peripheral intravenous cannula is therefore of great importance. Deficient care, handling and documentation of peripheral intravenous cannulae have previously been reported. DESIGN: A cross-sectional survey was conducted by a group of nurses at three wards at a university hospital before and after the implementation of the evidence-based guidelines. METHOD: A structured observation protocol was used to review the frequency of thrombophlebitis, the nurses' care, handling and the documentation of peripheral intravenous cannulae in the patient's record. RESULTS: A total of 107 and 99 cannulae respectively were observed before and after the implementation of the guidelines. The frequency of peripheral intravenous cannulae without signs of thrombophlebitis increased by 21% (P < 0.01) and the use of cannula size 0.8 mm increased by 22% (P < 0.001). Nurses' documentation of peripheral intravenous cannula improved significantly (P < 0.001). CONCLUSION: We conclude that implementation of the guidelines resulted in significant improvements by means of decreased frequency of signs of thrombophlebitis, increased application of smaller cannula size (0.8 mm), as well as of the nurses' documentation in the patient's record. RELEVANCE TO CLINICAL PRACTICE: Further efforts to ameliorate care and handling of peripheral intravenous cannulae are needed. This can be done by means of increasing nurses' knowledge and recurrent quality reviews. Well-informed patients can also be more involved in the care than is common today.