The successes of existing high speed rail systems; the Shinkansen in Japan and TGV in France, have been widely reported. This paper presents evidence of the benefits of HSR as reported by studies carried out on the existing high speed rail systems. There are many benefits attributed to high speed rail systems which can be broadly classified into: Social/Public benefits; Economic benefits and Environmental benefits. While widely reported and evident, there has however been very little research carried out to quantify the benefits to the respective countries in which HSR has been introduced. Although limited, the available research does suggest a positive net benefit to the economy as a whole.