Road collisions involving motorcyclists continue to represent a serious public health concern worldwide, including in New Zealand. It is widely accepted that one key factor in motorcyclist crashes around the world is the difficulty other road users have in detecting an approaching motorcyclist or correctly appraising their speed and position (typically at junctions). The Motorcycle Safety Advisory Council commissioned TRL to review the international literature on motorcycle conspicuity, to establish those treatments that might be most suitable for use or further validation work in New Zealand. The review used a systematic methodology for searching, inclusion, and assessing the quality of studies of treatments designed to improve motorcyclist conspicuity. The review concluded that, even when considering only the best quality studies, it has generally been shown that high visibility and reflective clothing, and headlights or daytime running lights on motorcycles, have been effective in increasing motorcyclist conspicuity. In addition, novel lighting configurations can be effective (especially at night), if for example they are designed to make motorcycles ‘stand out’ against other vehicles with lights, or to accentuate the visual profile of motorcycles and provide drivers with more visual information to judge time to arrival. There are limitations to all interventions, not least because conspicuity typically depends on a high visual contrast with the background, and this can vary from situation to situation. The review recommends that validation work on novel lighting configurations is defined and then taken forward in New Zealand, and that work continues to raise awareness among bikers as to the benefits (and limitations) of high visibility and reflective clothing.