Deficient routines in use, care, handling and documentation of peripheral intravenous vein cannulae (PIV) have previously been reported, and complications have been noted in 50-75% of the patients. The aim of the study was to examine whether specially trained nurses change their actions to decrease complications when using cannulae. The study included 36 nurses assigned to experimental and control groups. The experimental group followed an education programme explaining how to use and take care of a PIV. To evaluate the intervention document analysis, observations and patient interviews were performed in 99 patients with 172 PIVs in situ for less than 24 h. After the education programme, fewer complications, more carefully performed care and handling, and better documentation and information were found in the experimental group. Nurses in the control group followed current routines, which resulted in a greater degree of complications. Education in evidence-based care and handling gives nurses the opportunity to improve their ability to use theoretical knowledge in clinical problems.