This article describes an evaluation of seven sharp safety intravenous (IV) cannula devices in six Welsh NHS hospitals and the Welsh Ambulance Service. Products analysed included six passive devices designed to engage the safety feature automatically on withdrawal of the needle from the cannula and one active device that requires a button to be pressed to activate it. The companies concerned provided the devices and appropriate training. Participating healthcare workers used the safety device instead of the conventional device to perform IV cannulations during the evaluation and each type of device was evaluated in random order Participants filled in a questionnaire for each device and then a further questionnaire comparing each one at the end of the process. Results showed that two of the passive devices were the most preferred. Most users stated that they would use either of these devices instead of the conventional device. It was not possible to identify a favourite between these two devices. Some devices were considered to be unfavourable. The main disadvantages that users experienced included slow flashback (where venepuncture is confirmed by blood visibly entering the device), blood leakage from the back of the device and resistance when withdrawing the needle from the cannula.