Today real time kinematic GPS (RTK GPS) is the newest and the most common method utilized in tasks requiring real time positions with especially, centimeter accuracies. However, as with all good things in life, this contemporary method of positioning is not flawless, that is, not free from errors. As in static GPS, RTK GPS is also susceptible to multipath errors. This study aims to investigate this source of error and attempts to answers some questions such as how much multipath error causes real time positioning error, in what kind of environment this error is the most effective and how large the positional errors this multipath produces. For these reasons, the fundamental background on multipath error was first covered and the surrounding causing this effect was widely researched, hence a test environment was designed. Various analyses were conducted in light of the findings obtained from the tests carried out and conclusions and suggestions were made in detailed fashion so that they could lead the way to future researches.